News

October 2023

• On the 100th anniversary (Oct 29th, 2023) of our independent Turkish Republic, we commemorate with gratitude all our martyrs and veterans who enabled us to do science freely.
• A new article “Electronic Properties of a Novel Boron Polymorph: Ogee-Borophene” is published in Adv. Condens. Matter Phys.
• New version (v23.10.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. Please refer to release notes.

July 2023

• New version (v23.7.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. There are many new features in this version: Phonon calculations, energy consumption measurement, and more. Please refer to release notes.
• Tugce Han has finished her studies, passed her viva, and gained her title. Congratulations Tugce Han, MSc.

June 2023

• M. Taha Haliloğlu joined our group once again for his doctoral study. Welcome back, Taha.
• A. Fatih Kuloglu joined our group once again for his doctoral study. Welcome back, Fatih.
• Umit Sahin joined our group for his doctoral study. Welcome Umit.

March 2023

• A new article “Structural and optical properties of mist-CVD grown MgZnO: Effect of precursor solution composition” is published in Physica B.
• A new article “First principles calculations of electronic and optical properties of InSe nanosheets doped with noble metal atoms” is published in Comput. Mater. Sci.

February 2023

• New version (v23.2.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.
• Hakan Yakupoğlu has joined our group. Welcome, Hakan.

October 2022

• A new article “Effect of Sulfur Concentration on Structural, Optical and Electrical Properties of Cu2CoSnS4 Absorber Film for Photovoltaic devices” is published in Physica B.
• Volkan Uncu has joined our group. Welcome Volkan.

August 2022

• Our website is renewed with Just the Docs theme. It is more responsive, detailed, and ordered now.
• A new article “Morphological and optical characterizations of different ZnO nanostructures grown by mist-CVD” is published in J. Lumin.

July 2022

• Aestimo 1D version 3.0 is released. This is a major release nearly again 2 years later. Because the code base was complicated and the usage of Aestimo was hard to understand, this release is mostly a simplification and clean-up release. Please visit to release notes for more information.
• New version (v22.7.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

May 2022

• New version (v22.5.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

April 2022

• Gazi University accepts our new project CuOxMIST: Ga2O3/Cu2O p-n junction production and related computational studies with p-type Cu2O semiconductor thin films grown by Mist-CVD”. Congratulations.
• New version (v22.4.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

March 2022

• Beyza Lisesivdin, has been appointed a full professor to Gazi University, Faculty of Science, Department of Physics. Congratulations.
• New version (v22.3.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

February 2022

• Sefa Kazanc has joined our group. Welcome Sefa.
• Umut Caglar has joined our group. Welcome Umut.
• A new article “A Structural Analysis of Ultrathin Barrier (In)AlN/GaN Heterostructures for GaN‐based High‐frequency Power Electronics” is published in Surf. Interface Anal.

January 2022

• A new article “gpaw-tools–higher-level user interaction scripts for GPAW calculations and interatomic potential based structure optimization” is published in Comput. Mater. Sci.

December 2021

• New version (v21.12.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

November 2021

• Assoc. Prof. Dr. Beyza Sarıkavak Lişesivdin was entitled to receive support for 6 months to work at Ulm University, Germany, within the scope of the TÜBİTAK 2219 Program. Assoc. Prof. Dr. Sarıkavak Lişesivdin will study “NV defect-centered synthetic diamond augmentation and quantum optical characterizations” with Prof. Dr. Fedor Jelezko at the Institute of Quantum Optics.
• The second article in this month, “Investigation of Structural and Optical Properties of ZnO Thin Films Grown on Different Substrates by Mist-CVD Enhanced with Ozone Gas Produced by Corona Discharge Plasma which is a result of our D.E.H.A Project is published in Advances in Condensed Matter Physics.
• A new article, A novel hot carrier-induced blue light-emitting device, which is a joint study between Istanbul University, Antalya Bilim University, Bilkent University, Gazi University, and Eskisehir Technical University, is published in Journal of Alloys and Compounds.
• New version (v21.11.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

October 2021

• New version (v21.10.0) of gpaw-tools is released. It can be downloaded from gpaw-tools repository. You can find what’s new on the release notes page.

September 2021

• Prof. Lisesivdin and Assoc Prof. Sarikavak-Lisesivdin developed UI/GUI Python scripts for GPAW users to facilitate GPAW calculations easily. It is called gpaw-tools. It is distributed as open-source software and can be downloaded from https://github.com/lrgresearch/gpaw-tools. We have a website for gpaw-tools at here.

July 2021

• Mehmet Taha Haliloglu has joined our group. Welcome, Mehmet Taha.

June 2021

• Meltem Yayla has finished her studies, passed her viva, and gained her title. Congratulations Meltem Yayla, MSc.
• Polat Narin has finished his studies, passed his viva, and gained his title. Congratulations Dr. Narin.

April 2021

• The third article has been accepted in a month! “Effect of magnesium content and growth temperature on structural and optical properties of USCVD-grown MgZnO films” which is a result of our D.E.H.A Project is published in Applied Physics A.
• A new article “The effect of barrier layers on 2D electron effective mass in Al0.3Ga0.7N/AlN/GaN heterostructures”, which is a joint study between Gazi University, Eskisehir Technical University, Rzhanov Institute of Semiconductor Physics and Novosibirsk State University, is published in J. Phys.: Condens. Matt.
• A new article “Growth dynamics of mist-CVD grown ZnO nanoplatelets”, which is a result of our D.E.H.A Project is published in Physica B: Condensed Matter.

March 2021

• Meltem Yesiltepe is joined to our group. Welcome Meltem.

February 2021

• The Rector of Gazi University Prof. Dr. Musa Yıldız came together with the faculty members who contributed the most to our University with the TÜBİTAK and ERASMUS+ projects they carried out in the 2016-2020 period. Prof. Dr. S. B. Lisesivdin received a certificate of appreciation because of his contributions to our university with the projects he carried out.

January 2021

• Pakize Turhan has joined our group. Welcome, Pakize.
• Gul Ercetin has joined our group. Welcome Gul.

October 2020

• A new article “The effect of passivation layer, doping and spacer layer on electron-longitudinal optical phonon momentum relaxation time in Al0.3Ga0.7N/AlN/GaN heterostructures”, which is a result of a joint project between Gazi University, Eskisehir Technical University, Rzhanov Institute of Semiconductor Physics and Novosibirsk State University, is published in Mater. Sci. Semicond. Process.

September 2020

• Our “Structural parameters and electronic properties of 2D carbon allotrope: graphene with a kagome lattice structure” titled study is accepted at Chem. Phys. Lett. This study is a joint DFT study that was done at the University of Ulm visit between Nov. 2019 - Feb 2020.

• Reference paper for Aestimo 1D solver: “General-purpose open-source 1D self-consistent Schrödinger-Poisson Solver: Aestimo 1D” which gives a general overview of the Aestimo 1D has been published in Comput. Mater. Sci. Aestimo 1D is an open-source one-dimensional Schrödinger-Poisson solver project that is started by Prof. Lisesivdin in 2012.

May 2020

• We have attended the Kobit-4 Quantum Optics and Information meeting held online because of pandemic with two proceedings.
• Tugce Han is joined to our group. Welcome Tugce.

March 2020

• Congratulations! Polat Narin has been selected as an Outstanding Reviewer for Nanotechnology for 2019, in recognition of the high quality and timeliness of his reviews during the year.

February 2020

• Our first study of 2020 “Effects of Annealing under Different Atmospheres on Structural and Optical Properties of USCVD grown ZnO Nanostructures” is published at Mater. Sci. Eng. B. This study is a part of our TUBITAK project 116F197 and second experimental publication from this project. The study shows the effect of the usage of Argon and Oxygen atmospheres in the growth of ZnO nanoparticles in the Mist CVD growth method.

January 2020

• Meltem Yayla has joined our group. Welcome Meltem.
• Prof. Lisesivdin has returned from 3 month-long studies held at the Institute for Quantum Optics (IQO), University of Ulm. It was decided to increase the number of studies and collaboration between LRG and IQO.
• New publication “Investigation of electronic and optical properties of wurtzite MgZnO using GGA + U formalism” is currently published at Philos. Mag. Lett. journal. The study is providing a new way to find better electronic structure calculations where classical DFT approaches fell short.

Older News

Publications in 2019!

Dec 30 2019, by S. B. Lisesivdin

We have got 4 new publications in 2019

• P.Narin, J. M. All Abbas, G. Atmaca, E. Kutlu, S. B. Lisesivdin, E. Ozbay “Ab initio Study of Electronic Properties of Armchair Graphene Nanoribbons Passivated with Heavy Metal Elements” Solid State Commun. 296, 8 (2019).
• P. Narin, E. Arslan, M. Ozturk, M. Ozturk, S. B. Lisesivdin, E. Ozbay “Scattering analysis of ultrathin barrier (< 7 nm) GaN-based heterostructures” Appl. Phys. A Mater. Sci. Process. 125, 278 (2019).
• J. M. All Abbas, P. Narin, E. Kutlu, S. B. Lisesivdin, E. Ozbay “Electronic properties of Zigzag ZnO nanoribbons with Hydrogen and Magnesium passivations” Physica B 556, (2019).
• R. Ibrahem, P. Narin, S. B. Lisesivdin, E. Ozbay “Investigation of electronic and optical properties of wurtzite MgZnO using GGA+U formalism” Phil. Mag. Lett. 99, 11 (2019)

Thanks to all colleagues, who made these publications possible.

Kemal Berk Sönmez is graduated. Congratulations Mr. Sönmez, MSc.

June 12 2019, by S. B. Lisesivdin

This year’s second and seemed to be the last graduation from the group! Kemal Berk Sönmez has finished his MSc studies about the fabrication and characterization of TaN resistors for GaN-based MMIC systems. Congratulations Kemal Berk!

Mehmet Taha Haliloğlu is graduated. Congratulations Mr. Haliloğlu, MSc.

May 15 2019, by S. B. Lisesivdin

This year’s first graduation! Mehmet Taha Haliloğlu has finished his MSc studies about the application of the back side via etching on SiC substrates for the fabrication of GaN-based field effect transistors. He is continuing to work at Bilkent Nanotam - ABMikroNano Complex as a senior engineer. Congratulations Mehmet Taha!

Publications in 2018!

Jan 7 2019, by P. Narin

We have got 5 new publications in 2018

• J.-H. Lee, J.-M. Ju, G. Atmaca, J.-G. Kim, S.-H. Kang, Y. S. Lee, S.-H. Lee, J.-W. Lim, H.-S. Kwon, S. B. Lisesivdin, J.-H. Lee “ High Figure-of-Merit (V2BR/RON) AlGaN/GaN Power HEMT With Periodically C-Doped GaN Buffer and AlGaN Back Barrier” IEEE J. Electron Dev. Soc. 6, 1179 (2018).
• O. Omeroğlu, E. Kutlu, P. Narin, S. B. Lisesivdin, E. Ozbay “Electronic Properties of Graphene Nanoribbons Doped with Zinc, Cadmium, Mercury Atoms” Physica E 104, 124 (2018).
• G. Atmaca, P. Narin, E. Kutlu, T. V. Malin, V. G. Mansurov, K. S. Zhuravlev, S. B. Lisesivdin, E. Ozbay, “Negative Differential Resistance Observation and a New Fitting Model for Electron Drift Velocity in GaN-Based Heterostructures” IEEE Trans. Electron Dev. 65, 950 (2018).
• P. Narin, E. Kutlu, G. Atmaca, A. Atilgan, A. Yildiz. S. B. Lisesivdin, “Structural and optical properties of hexagonal ZnO nanostructures grown by ultrasonic spray CVD” Optik 168, 86 (2018).
• E. Kutlu, P. Narin, S. B. Lisesivdin, E. Ozbay “Electronic and optical properties of black phosphorus doped with Au, Sn and I atoms” Philos. Mag. 98, 155 (2018).

Thanks to all colleagues, who made these publications possible.

Rokaia Ibrahem has graduated. Congratulations Ms. Ibrahem, MSc.

Sep 21 2018, by S. B. Lisesivdin

Fourth graduation of this year! Rokaia Ibrahem has finished her MSc studies about the studying the electronic and optical properties of wurtzite MgZnO compound with DFT methods with a superior accuracy. Congratulations Rokaia!

Our start-up company application is supported by TUBITAK!

Aug 17 2018, by S. B. Lisesivdin

Our start-up company plan for building a UV-VIS-NIR spectrometer is financially supported by TUBITAK! This year TUBITAK received 3323 entrepreneurial business ideas for Phase 0. Then, 1438 entrepreneurs from these applications received Phase I support. Of these entrepreneurs prepared by the related organizations in their technical and business development areas, 422 were accepted for panel evaluations in accordance with the application requirements. TUBİTAK conducted by the academicians, industrialists, and investors of the panel evaluation of the results of the 146 entrepreneurs who were eligible to pass Phase II (result). Our company is one of them! More news is coming soon.

Our project has passed the first phase of the TUBITAK 1003 program

Aug 09 2018, by S. B. Lisesivdin

Our project, which is about to produce the “national” random number generator up to 40 Gbit/s, has passed the first phase of the TUBITAK 1003 program. We have already started to finalize the draft of the submission of the second phase. The due date for the submissions for the second phase is November 2018.

Oznur Omeroglu has graduated. Congratulations Ms. Omeroglu, MSc.

Jun 04 2018, by S. B. Lisesivdin

Two graduations in a single day! Oznur Omeroglu has finished her MSc studies investigating the effects of heavy metal doping on the electronic properties of graphene. Congratulations.

Mehmet Ozturk has graduated. Congratulations Mr. Ozturk, MSc.

Jun 04 2018, by S. B. Lisesivdin

Mehmet Ozturk has finished his MSc studies investigating the electrical properties of ultrathin barrier GaN HEMTs. Congratulations.

Dr. Lisesivdin appointed as a full professor

Mar 21 2018, S. B. Lisesivdin

Sefer Bora Lisesivdin has been appointed full professor at Gazi University, Faculty of Science, Department of Physics.

Gokhan Atmaca has graduated. Congratulations Dr. Atmaca

Jan 10 2018, by S. B. Lisesivdin

Gokhan Atmaca has finished his studies and gained his title. Congratulations.

Publications in 2017!

Jan 10 2018, by S. B. Lisesivdin

We have got 6 new publications in 2016:

• P. Narin, E. Kutlu, G. Atmaca, S. B. Lisesivdin, E. Ozbay “A first principles investigation of the effect of aluminum, gallium, and indium impurities on optical properties of B-Si3N4 structure” Optik 147, 115 (2017).
• J. M. Al Abbas, P. Narin, G. Atmaca, E. Kutlu, B. Sarikavak-Lisesivdin, S. B. Lisesivdin “The effect of doping in different layers on 2DEG for ultrathin-barrier AlN/GaN heterostructures” Optoelectron. Adv. Mater.-Rapid Comm. 11, 328 (2017).
• J. M. All Abbas, G. Atmaca, P. Narin, E. Kutlu, B. Sarikavak-Lisesivdin, S. B. Lisesivdin “A Comparative Study of AlGaN and InGaN Back-Barriers in Ultrathin-Barrier AlN/GaN Heterostructures” J. Elec. Mater. 46, 5278 (2017).
• E. Kutlu, P. Narin, G. Atmaca, B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “Electronic structure of β-Si3N4 crystals with substitutional icosagen group impurities” J. Optoelectron. Adv. Mater. 19, 278 (2017).

Thanks to all colleagues, who made these publications possible.

Aestimo v.1.2.0 is released!

Nov 06 2017, by S. B. Lisesivdin

Nearly one year passed and the new version (v.1.2.0) of Aestimo is ready! Thanks to Robert Steed and Hamza Hebal for their efforts to make Aestimo better. We hope that you enjoy it.

Some new features of Aestimo:

• Quaternary alloys (type A_{x}B_{1-x}C_{y}D_{1-y})
• Added an improved model for modeling conduction band intersubband transitions
• Added a periodic boundary condition for the Electric field for modeling repeating structures.
• Small changes were made like getting Aestimo to work on python3.4, example files were renamed to be more pythonic etc …
• Code is moved to GitHub.

Aestimo has a DOI number:

R. Steed, H. Hebal, and S. B. Lisesivdin. (2017, November 6). sblisesivdin/aestimo: Version v.1.2 (Version v.1.2.0). Zenodo. http://doi.org/10.5281/zenodo.1042657

Version 1.2 can be downloaded from this link. Aestimo is GPL-licensed software. Any improvements, bug reports, or feedback are welcome.

2016 TÜBA “International Academy Prizes, GEBİP and TEÇEP Awards” were handed to the owners and Dr. Lisesivdin received his TUBA / GEBIP Award

Feb 1 2017, by S. B. Lisesivdin

2016 TÜBA “International Academy Prizes, GEBİP and TEÇEP Awards” were handed to the owners under the auspices of the Presidency with the ceremony held on February 1, 2017, in the Presidential Complex. Assoc. Prof. Sefer Bora Lisesivdin was awarded the TÜBA GEBİP Prize in the category of Physics. He received his award from deputies of Prime Minister Nurettin Canikli.

Publications in 2016!

Jan 10 2017, by P. Narin

We got 6 new publications in 2016:

• P. Narin, E. Kutlu, B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “ Electronic properties of Li-doped zigzag graphene nanoribbons” Physica E 84, 543-547 (2016).
• E. Kutlu, P. Narin, G. Atmaca, B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “ Effect of substitutional As impurity on electrical and optical properties of b-Si3N4 structure” Mater. Res. Bull. 83, 128-134 (2016).
• I. Kara, Y. Sarikavak, S. B. Lisesivdin, M. Kasap “Evaluation of Morphological and Chemical Differences of Gunshot Residues in Different Ammunitions Using SEM/EDS Technique” Environ. Foren. 17, 68 (2016).
• G. Atmaca, P. Narin, B. Sarikavak-Lisesivdin, S. B. Lisesivdin “Two Dimensional Electron Gas in a Hybrid GaN/InGaN/ZnO Heterostructure with Ultrathin InGaN Channel Layer” Physica E 79, 67 (2016).
• G. Atmaca, S. Ardali, E. Tiras, T. Malin, V.G. Mansurov, K.S. Zhuravlev, S.B. Lisesivdin, “Scattering analysis of 2DEG mobility in undoped and doped AlGaN/AlN/GaN heterostructures with an in situ Si3N4 passivation layer”, Solid-State Electronics 118, 12-17 (2016).
• G. Atmaca, S. Ardali, P. Narin, E. Kutlu, S. B. Lisesivdin, T. Malin, V. Mansurov, K. Zhuravlev, E. Tiras “Energy relaxation of hot electrons by LO phonon emission in AlGaN/AlN/GaN heterostructure with in situ Si3N4 passivation” J. Alloys Compounds 659, 90 (2016).

Thanks to all colleagues, who made these publications possible.

Dr. Lisesivdin is selected for the Prestigious TUBA / GEBIP Award

Nov 1 2016, by S. B. Lisesivdin

Dr. Sefer Bora Lisesivdin has been awarded with the Turkish Academy of Sciences, Distinguished Young Scientist Award for 2016 in the field of Physics. In the framework of this GEBIP program of the TUBA, his research activities will be supported for a period of 3 years. The objective of TÜBA-GEBIP is to foster young, outstanding scientists who are at the stage of establishing their own research programs in Turkey after finishing their post-doctoral research activities. TÜBA supports these scientists for a period of three years and helps them set up their own research groups at a stage when they are in need of incentives.

Ph.D. student Gokhan Atmaca earned a research scholarship

Mar 21 2016, by S. B. Lisesivdin

Gokhan Atmaca, who is a PhD student in our group, earned a TUBITAK 2214 international research scholarship. He will conduct his research project at the Nitride Semiconductor Device Laboratory, which is located at Kyungpook University, South Korea. His research will continue for 8 months. Congratulations Gökhan!

Publications in 2015!

Dec 31 2015, by G. Atmaca

We got 5 new publications in 2015:

• S. Ardali, G. Atmaca, S. B. Lisesivdin, T. Malin, V. Mansurov, K. Zhuravlev, E. Tiras “The variation of temperature-dependent carrier concentration and mobility in AlGaN/AlN/GaN heterostructure with SiN passivation” Phys. Stat. Sol. B 252, 1960 (2015).
• I. Kara, S. B. Lisesivdin, M. Kasap, E. Er, U. Uzek “The Relationship between the Surface Morphology and Chemical Composition of Gunshot Residue Particles” J. Foren. Sci. 60, 1030 (2015).
• B. Sarikavak-Lisesivdin, S. B. Lisesivdin, N. Balkan, G. Atmaca, P. Narin, H. Cakmak, E. Ozbay “Energy relaxation of electrons in InGaN quantum wells” Metall. Mater. Trans. A 46, 1565 (2015).
• G. Atmaca, P. Narin, B. Sarikavak-Lisesivdin, S. B. Lisesivdin, M. Kasap “Electron Transport Properties of Two Dimensional Electron Gas in BexZn1-xO/ZnO Heterostructures” Philos. Mag.95, 79 (2015).
• G. Atmaca, P. Tasli, G. Karakoc, E. Yazbahar and S. B. Lisesivdin “Numerical Investigation of the 2DEG Properties of AlGaN/AlN/GaN HEMT Structures with InGaN/GaN MQW Back-Barrier Structure” Physica E 65, 110 (2015).

Thanks to all colleagues, who made these publications possible.

Dr. S. B. Lisesivdin Earns IEEE Senior Membership

Aug 29 2015, by Dr. S. B. Lisesivdin

Dr. Sefer Bora Lisesivdin has been recently elevated to the grade of Senior Member of the IEEE. Senior Member is the highest professional grade of the IEEE for which a member may apply and only about 7 percent of IEEE’s 430,000 members have achieved this level.

To be eligible for Senior Member status, IEEE members must be engineers, scientists, educators, technical executives, or originators in IEEE-designated fields with at least 10 years of experience; have experience reflecting professional maturity; and show significant performance throughout at least five of their years in professional practice.

IEEE is the world’s largest professional association dedicated to advancing technological innovation and excellence for the benefit of humanity. IEEE and its members inspire a global community through IEEE’s highly cited publications, conferences, technology standards, and professional and educational activities.

New Website

Apr 09 2015, by Dr. S. B. Lisesivdin

Our group will continue its studies as Gazi University Physics Department Lisesivdin Research Group (LRG).

Dr. Beyza Lisesivdin Earned Associate Professor Title

Mar 16 2015, by Dr. S. B. Lisesivdin

Dr. Beyza Lişesivdin received the rank of Associate Professor from the Turkish Inter-University Council (UAK) this Monday. Congratulations!

New Grant Received From TUBITAK

Mar 15 2015, by Dr. S. B. Lisesivdin

Dr. Beyza Lisesivdin received a grant from The Scientific and Technological Research Council of Turkey (TUBITAK). The project is about the investigation of the relationship between the properties of two-dimensional electronic gas and the surface structure of ultrathin barrier GaN-based High Electron Mobility Transistors (HEMTs). The project will be held between 2014-2016 and today the project is started.

New Article published in Physica E

2014-09-26 14:33, by G. Atmaca

Our recent work about 2DEG properties of AlGaN/AlN/GaN HEMT structures with InGaN/GaN MQW back-barrier structure was published in Physica E: Low-dimensional Systems and Nanostructures. http://dx.doi.org/10.1016/j.physe.2014.09.004.

Version 1.0 and the elementary version of Aestimo Solver have been released!

2014-08-29 22:21, by Dr. S. B. Lisesivdin

The Aestimo Team is proud to release version 1.0 of Aestimo 1D Self-consistent Schrödinger-Poisson Solver. This version includes many bug fixes, a new organization of the structure, wurtzite material use, and lots of changes in the intersubband optical transitions module. Dielectric constants are now handled more accurately. Many tutorials are added in the form of an ipython notebooks. The code is heavily modified and stabilized with more than 60 commits. This version is the most feature-rich and stable version ever. For more please visit the release notes. Also, another aestimo version, which is called “elementary” is released. This version is easy to understand in terms of coding, and therefore it can be used in undergraduate/graduate courses and forking new solvers. There will be no other release for the “elementary” version. We are always open to your contributions. Please use it, issue a bug, help to write use a better user’s manual, or commit to source!

Dr. Sarikavak-Lisesivdin and Dr. Lisesivdin earned publication and citation awards

2014-06-14 10:10, by NDCT

Dr. Sarikavak-Lisesivdin and Dr. Lisesivdin earned publication and citation awards from Gazi University. Awards are presented in the ceremony which is held on June 23rd, 2014 at Gazi University, Ankara. Click here for pictures.

Dr. Lisesivdin earned the Young Scientist award

2014-06-14 10:10, by NDCT

Turkish Society of Physics has awarded Dr. Lisesivdin with the 2014 YEAR OF TURKISH SOCIETY OF PHYSICS PROF. DR. SEVKET ERK YOUNG SCIENTIST AWARD. The award will be presented at the TPS 31. International Physics Congress which will be held at Bodrum, Turkey from July 21st-24th 2014.

New Article published in Physica E

2014-05-26 18:12, by Dr. S. B. Lisesivdin

Our recent work on the extraction of mixed conduction in graphene-on-SiC systems was published in Physica E: Low-dimensional Systems and Nanostructures.

New grant received from TUBITAK/RFBR 2532 coded international collaboration program

2014-02-07 22:23, by Dr. S. B. Lisesivdin

We received a joint grant from the Scientific and Technological Research Council of Turkey (TUBITAK) and RFBR of Russia. The project is about the manipulation of the properties of two-dimensional electronic gas using in-situ surface passivation of AlGaN/GaN heterostructures by molecular beam epitaxy and will be held between 2014-2016. Dr. Lisesivdin will be the project investigator of the project.

Publications in 2013!

2014-01-09 11:12, by Dr. S. B. Lisesivdin

We got 3 new publications in 2013:

• K. Elibol, G. Atmaca, P. Tasli, and S. B. Lisesivdin “A Numerical Study on Subband Structure of InxAl1-xN/GaN-Based HEMT Structures with Low-Indium (x<0.10) Barrier Layer” Solid State Commun. 162, 8 (2013).
• A. F. Kuloglu, B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “First-principles calculations of Pd-terminated symmetrical armchair graphene nanoribbons” Comp. Mater. Sci. 68, 18 (2013).
• B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “The Effect of InxGa1-xN Back-barriers on the Dislocation Densities in Al0.31Ga0.69N/AlN/GaN/ InxGa1-xN/GaN Heterostructures (0.05 ≤ x ≤ 0.14)” Cur. Appl. Phys. 13, 224 (2013).

Thanks to all colleagues, who made these publications possible.

XIX. Solid State Matter Physics Ankara Meeting and COST MP0805 Final Meeting

2014-01-01 20:32, by G. Atmaca

We have attended to XIX. Solid State Matter Physics Ankara Meeting helded at Bilkent University in 20 December 2013 and COST MP0805 Final Meeting helded at Istanbul University Science Faculty between 24 – 26 September 2013. In this exciting congresses, we have presented two studies:

• S. B. Lisesivdin, G. Atmaca, E. Arslan, J. Ul-Hassan, E. Janzén, E. Ozbay “SiC üzerine büyütülen grafen yapılarda elektriksel iletim kanallarının ayrıştırılıp incelenmesi XIX. Solid State Matter Physics Ankara Meeting, S13, (2013). [Invited].
• S.B. Lisesivdin, N. A. Khan, S. Mazzucato, N. Balkan, M. J. Adams “Gain in electrically-driven 1.3 um dilute nitride VCSOAs” COST MP0805 Final Meeting, Istanbul, P17 (2013).

Thanks to all…

Aestimo v.0.9 is released!

2013-09-16 18:36, by Dr. S. B. Lisesivdin

The Aestimo Team is proud to release version 0.9 of Aestimo 1D Self-consistent Schrödinger-Poisson Solver. This version includes many bug fixes, speed improvements, cython code additions, rewritten VBMAT-V part to use numpy better, merging conduction and valance band calculations, and more. The code is heavily modified and stabilized.

Version 0.9 can be downloaded from https://bitbucket.org/sblisesivdin/aestimo/downloads Aestimo is GPL licensed software. We are always open to your contributions. Please use it, issue a bug, help to write use a better user’s manual, or commit to source!

Turkish Physical Society International Physics Congress #30

2013-09-16 18:36, by G. Atmaca

We attended to 30th International Physics Congress organized by the Turkish Physical Society held at Istanbul University Science Faculty between 2 – 5 September 2013. In this exciting congress, we have presented three papers:

• P. Narin, G. Atmaca, E. Boyalı, S. B. Lisesivdin, M. Kasap, S. Ozcelik, “Scattering Analysis of 2DEG in AlInN/GaN Based Heterostructures with GaN and InGaN Quantum Wells”, Turkish Physical Society 30th International Physics Congress, p530 (2013).
• E. Boyalı, P. Narin, G. Atmaca, S. B. Lisesivdin, M. Kasap and S. Ozcelik, “The Investigation of Temperature Dependent Electrical Transport Properties of InxGa1-xP/GaAs”, Turkish Physical Society 30th International Physics Congress, p482 (2013).
• P. Narin, G. Atmaca, B. Sarıkavak-Lisesivdin, S. B. Lisesivdin, M. Kasap, “A Numerical Investigation on Electronic Properties of Two Dimensional Electron Gas in BexZn1-xO/ZnO Heterostructures”, Turkish Physical Society 30th International Physics Congress, p529 (2013).

Thanks to all …

Version 0.8 of the Aestimo solver has been released!

2013-07-07 11:06, by Dr. S B. Lisesivdin

The Aestimo Team is proud to release version 0.8 of Aestimo 1D Self-consistent Schrödinger-Poisson Solver. This version includes many new features, bug fixes, and small corrections. The most important feature, which has been added to Aestimo recently, is the implementation of strain-included valence band calculation with a 3×3 k.p model. Also, the Numpy version is restructured, the input file structure and sample inputs are changed and the non-parabolicity of the conduction band is implemented (Numpy version only). In addition, the database is changed to a more clear-understandable structure, and exchange interaction potential is implemented (Numpy version only). Logging with timers, some customizations in the config, and the possibility of looping the simulation over a parameter are also the added to new version. Aestimo can work now with new materials InAs, InP, AlP, GaP, and new alloys InGaAs, InGaP, and AlInP in addition to GaAs and AlGaAs.

Version 0.8 can be downloaded from https://bitbucket.org/sblisesivdin/aestimo/downloads Aestimo is GPL licensed software. We are always open to your contributions. Please use it, issue a bug, help to write use a better user’s manual, or commit to source!

Publications in 2012!

2013-02-08 00:07, by Dr. S. B. Lisesivdin

We got 3 new publications in 2012:

• B. Sarikavak-Lisesivdin, S. B. Lisesivdin, E. Ozbay “Ab initio study of Ru-terminated and Ru-doped armchair graphene nanoribbons” Mol. Phys. 110, 2295 (2012).
• E. Tiras, O. Celik, S. Mutlu, S. Ardali, S. B. Lisesivdin, E. Ozbay “Temperature-dependent energy relaxation time in AlGaN/AlN/GaN heterostructures” Superlat. Microstruct. 51, 733 (2012).
• O. Celik, E. Tiras, S. Ardali, S. B. Lisesivdin, E. Ozbay “Determination of the LO phonon energy and alloy scattering potential in AlGaN/GaN HEMTs” Cent. Eur. J. Phys. (2012).

Thanks to all colleagues, who made them possible.

Group member, C. Gunes, MSc. is graduated!

2013-01-23 21:06, by Dr. S B. Lisesivdin

Group member, C. Gunes, MSc. graduated this week. Congratulations.

Publications in 2011!

2012-01-05 21:46, by Dr. S. B. Lisesivdin

We got 2 new publications in 2011:

• O. Kelekci, S. B. Lisesivdin, S.Ozcelik, E. Ozbay “Numerical optimization of In-mole fraction and layer thicknesses in AlxGa1-xN/AlN/GaN high electron mobility transistors with InGaN back barrier” Physica B 406, 1513 (2011).
• A. Yildiz, P. Tasli, B. Sarikavak, S. B. Lisesivdin, M. K. Ozturk, M. Kasap, S. Ozcelik, E. Ozbay “Grain boundary related electrical transport in Al-rich AlxGa1-xN layers grown by metal-organic chemical vapor deposition” Semiconductors+ 45, 33 (2011).

Thanks to all colleagues, who made them possible.

New publications in 2010 #2

2011-01-05 21:44:08, by Dr. S. B. Lisesivdin

We got 3 new publications in the second half of 2010:

• H. Yu, S. B. Lisesivdin, B. Bolukbas, O. Kelekci, M. K. Ozturk, S. Ozcelik, D. Caliskan, M. Ozturk, H. Cakmak, P. Demirel and E. Ozbay “Improvement of breakdown characteristics in AlGaN/GaN/AlxGa1-xN HEMT based on a grading AlxGa1-xN buffer layer” Phys. Stat. Sol. a 207, 2593 (2010).
• P. Tasli, B. Sarikavak, G. Atmaca, K. Elibol, A. F. Kuloglu and S. B. Lisesivdin “Numerical Simulation of Novel Ultrathin Barrier n-GaN/InAlN/AlN/GaN HEMT Structures: Effect of In Mole Fraction, Doping and Layer Thicknesses” Physica B 405, 4020 (2010).
• A. Bengi, S. B. Lisesivdin, M. Kasap, T. Mammadov, S. Ozcelik, E. Ozbay “Analysis of defect-related optical transitions in AlGaN/GaN heterostructures” Mater. Sci. Semicond. Process. 13, 105 (2010).

Thanks to all colleagues, who made them possible.

Group member, G. Karakoc, MSc. is graduated!

2013-01-03 21:05:11, by Dr. S. B. Lisesivdin

Group member, G. Karakoc, MSc. graduated this week. Congratulations.

Dr. S. B. Lisesivdin is supported by the Scientific and Technological Council of Turkey

2012-12-31 12:54:20, by Dr. S. B. Lisesivdin

Assoc. Prof. Dr. S. B. Lisesivdin is supported by the Scientific and Technological Council of Turkey (TUBITAK) for 6 months of study at the University of Essex, UK. Dr. Lisesivdin will start the studies in March 2013.

Group member, K. Elibol, MSc. is graduated!

2012-12-25 16:53:27, by Dr. S. B. Lisesivdin

Group member, K. Elibol, MSc. graduated this week. Congratulations.

Group member G. Atmaca, MSc. is graduated!

2012-06-05 14:52:19, by Dr. S. B. Lisesivdin

Group member, G. Atmaca, MSc. graduated this week. Congratulations.

Group member A. F. Kuloglu, MSc. graduated!

2012-05-29 12:47:17, by Dr. S. B. Lisesivdin

Group member, A. F. Kuloglu, MSc. graduated this week. Congratulations.

Two new university research projects are accepted!

2012-05-15 09:45:57, by Dr. S. B. Lisesivdin

Our group’s two new university research projects have been accepted. These projects are computational studies and therefore they are aimed to provide new hardware to the group’s computational facilities.

New rank for Dr. Lisesivdin

2011-10-09 12:44:34, by Dr. S. B. Lisesivdin

Dr. Sefer Bora Lisesivdin received the rank of Associate Professor from the Turkish Inter-University Council (UAK) this Friday.

Condensed Matter Physics Ankara Meetings #17

2010-11-07 11:41:08, by Dr. S. B. Lisesivdin

We have attended to 17. Condensed Matter Physics Ankara Meeting with 3 oral and 3 poster proceedings. This year 17. The condensed Matter Physics Ankara Meeting was held at Ankara University on Nov 5th, 2010. Here is the list:

• K. Elibol, O. Kelekci, G. Atmaca, S. B. Lisesivdin, M. Kasap, S. Ozcelik and E. Ozbay “Grafen Flake Uretim Yontemlerinin Gelistirilmesi” XVII. Solid State Matter Physics Ankara Meeting, S2 (2010).
• G. Atmaca, K. Elibol, P. Tasli, S. B. Lisesivdin, M. Kasap “Eklem Alan Etkili Transistorlerin Elektriksel Karakteristiklerinin Incelenmesi” XVII. Solid State Matter Physics Ankara Meeting, S12 (2010).
• O. Kelekci, S. B. Lisesivdin, M. Kasap, S. Ozcelik, E. Ozbay “InGaN arka bariyerli Al_{x}Ga_{1-x}N/AlN/GaN HEMT yapilarindaki ince filmlerin alasim oranlari ve kalinliklarinin numerik optimizasyonu” XVII. Solid State Matter Physics Ankara Meeting, S17 (2010).
• K. Elibol, G. Atmaca, P. Tasli, S. B. Lisesivdin and M. Kasap “GaN Tabanli MESFET Yapilarin 2-boyutta Elektriksel Karakteristikleri” XVII. Solid State Matter Physics Ankara Meeting, P34 (2010).
• A. F. Kuloglu, S. B. Lisesivdin, M. Kasap “GaAs Tabanli Bir MOSFET Yapinin 2-Boyutta Akim - Gerilim Karakteristiklerinin Incelenmesi” XVII. Solid State Matter Physics Ankara Meeting, P88 (2010).
• O. Kartaloglu, G. Atmaca, K. Elibol, S. B. Lisesivdin “Erbiyum Katkili Eklem Diyotun I-V Karakteristigi” XVII. Solid State Matter Physics Ankara Meeting, P46 (2010).

New publications in 2010 #1

2010-07-27 16:40:06, by Dr. S. B. Lisesivdin

We got 5 new publications in the last few months:

• S. Gokden, R. Tulek, A. Teke, J. H. Leach, Q. Fan, J. Xie, U. Ozgur, H. Morkoc, S. B. Lisesivdin, E. Ozbay “Mobility limiting scattering mechanisms in nitride-based two-dimensional heterostructures with InGaN channel” Semicond. Sci. Technol. 25, 045024 (2010).
• A. Yildiz, S. B. Lisesivdin, M. Kasap, D. Mardare “The substrate temperature effect on the electrical properties of titanium oxide thin films” J. Mater. Sci.: Mater. Electron. 21, 692 (2010).
• S. B. Lisesivdin, P. Tasli, M. Kasap, M. Ozturk, E. Arslan, S. Ozcelik, and E. Ozbay “Double subband occupation of the two-dimensional electron gas in In_{x}Al_{1-x}N/AlN/GaN/AlN Heterostructures with Low Indium Barrier (0.064 < x < 0.139)” Thin Solid Films 518, 5572 (2010).
• P. Tasli, A. Yildiz, M. Kasap, E. Ozbay, S. B. Lisesivdin, S. Ozcelik “Contributions of the impurity band and electron-electron interactions to the magnetoconductance of AlGaN” Philos. Mag. 90, 3591 (2010).
• S. B. Lisesivdin, A. Yildiz, N. Balkan, M. Kasap, S. Ozcelik, E. Ozbay “Scattering Analysis of Two-dimensional Electrons in AlGaN/GaN with Bulk Related Parameters Extracted by Simple Parallel Conduction Extraction Method” J. Appl. Phys. 108, 013712 (2010).

Thanks to all colleagues, who made them possible.

Venimus, Vidimus, Vincemus*

2010-05-16 18:39:10, by Dr. S. B. Lisesivdin

Two senior students from our laboratory (Mr. K. Elibol and Mr. G. Atmaca) got 1st and 2nd places in competition with the projects studied in our laboratory. The competition was for physics senior students and was held at Bilkent University on May 15th, 2010. Mr. K. Elibol’s study was about numerical optimization and device characterization of AlGaN/GaN-based HEMT structure with InGaN back barriers. Mr. G. Atmaca’s study was about the numerical optimization of the Double AlInN barrier for GaN-based HEMT structures. Congratulations folks!

*: ”“We came, we saw, we conquer””

New publications in 2010 #1

2010-01-17 10:38:28, by Dr. S. B. Lisesivdin

We got 3 new publications in the last few months:

• P. Tasli, S. B. Lisesivdin, A. Yildiz, M. Kasap, E. Arslan, E. Ozbay, and S. Ozcelik, “Well parameters of two-dimensional electron gas in Al0.88In0.12N/AlN/GaN/AlN heterostructures grown by MOCVD” Cryst. Res. Tech. 45, 133 (2010).
• A. Yildiz, S. B. Lisesivdin, M. Kasap, S. Ozcelik, E. Ozbay, and N. Balkan “Investigation of low-temperature electrical conduction mechanisms in highly resistive GaN bulk layers extracted with SPCEM” Appl. Phys. A 98, 557 (2010).
• A. Yildiz, S. B. Lisesivdin, P. Tasli, E. Ozbay, and M. Kasap “Determination of the critical indium composition corresponding to the metal-insulating transition in InxGa1-xN (0.06 < x < 0.135) layers” Curr. Appl. Phys. 10, 838 (2010).