Article
Chemistry, Physical
Jacek Piechota, Stanislaw Krukowski, Bohdan Sadovyi, Petro Sadovyi, Sylwester Porowski, Izabella Grzegory
Summary: This study investigates the behavior of GaN crystal at high temperatures and pressures, revealing that it undergoes thermal decomposition and congruent melting. Simulation results are in excellent agreement with experimental data, providing valuable insights into the physical properties of GaN.
CHEMISTRY OF MATERIALS
(2023)
Article
Physics, Applied
Yao Chen, Camille Haller, Wei Liu, Sergey Yu Karpov, Jean-Francois Carlin, Nicolas Grandjean
Summary: This study investigates the impact of GaN-buffer growth temperature on the efficiency of InGaN/GaN quantum wells, revealing that high-temperature growth promotes the creation of surface defects leading to a collapse in internal quantum efficiency. Theoretical analysis suggests that these defects are likely to be nitrogen vacancies. Furthermore, the study shows that surface defects are mainly generated at the early stage of GaN growth and reach a steady state concentration determined by the growth temperature.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Danni Chen, Jing Ning, Dong Wang, Boyu Wang, Jianglin Zhao, Jincheng Zhang, Yue Hao
Summary: GaN on graphene/Al2O3 substrates compensates for the defects caused by MOCVD on mismatched substrates. An intermediate layer of AlN or ZnO nanowalls is needed to provide sufficient nucleation sites on graphene without dangling bonds. High-quality GaN crystals with low compressive stress and dislocation density were successfully synthesized on nitrogen-doped graphene by MOCVD. The improved adsorption energy of Ga atom on nitrogen-doped graphene and atomic nitrogen pretreatment on monolayer graphene contribute to the nucleation of GaN films.
SCIENCE CHINA-MATERIALS
(2023)
Article
Chemistry, Physical
Hanof Alkhaldi, Peter Kroll
Summary: In this study, a pressure-temperature phase diagram of the iron-nitrogen system was obtained using computational methods. The chemical potential of nitrogen and its variation under high pressure and high temperature were assessed. The results are consistent with experimental data and predict a new high-pressure nitrogen-rich compound.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Jingyu Hou, Xiao-Ji Weng, Artem R. Oganov, Xi Shao, Guoying Gao, Xiao Dong, Hui-Tian Wang, Yongjun Tian, Xiang-Feng Zhou
Summary: The energy landscape of helium-nitrogen mixtures has been explored through ab initio evolutionary searches, leading to the prediction of several stable compounds in the pressure range from 25 to 100 GPa. Among these compounds, HeN22 and HeN20 may have high energy densities, making them promising materials for high-energy applications.
Article
Chemistry, Physical
You-Chen Weng, Ming-Yao Hsiao, Chun-Hsiung Lin, Yu-Pin Lan, Edward-Yi Chang
Summary: A high-pressure GaN nucleation layer was inserted in an AlGaN/GaN HEMT to improve its electrical properties. By optimizing the V/III ratio during the growth of the high-pressure GaN layer, the edge dislocation density in the layer was significantly reduced. Experimental results showed lower off-state leakage current, higher maximum I-D and G(m), and lower on-state resistance, indicating the effectiveness of the high-pressure GaN nucleation layer in enhancing the performance of the AlGaN/GaN HEMT.
Article
Materials Science, Multidisciplinary
Shaoqian Lu, Guohao Yu, Yingfei Sun, Xu Yuan, Zhongkai Du, Bingliang Zhang, Lu Wang, Yu Li, Dongdong Wu, Zengli Huang, Zhongming Zeng, Xulei Qin, Baoshun Zhang
Summary: In this article, a method of nitrogen plasma treatment is proposed to achieve normally off p-GaN/AlGaN/GaN high-electron-mobility transistors, and the related mechanism is proposed. The nitrogen plasma treatment depletes holes in the p-GaN layer and changes the surface characteristics, resulting in the formation of a 2D electron gas at the AlGaN/GaN interface. The device shows enhanced performance with improved threshold voltage, on/off ratio, and maximum drain current.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Materials Science, Multidisciplinary
M. M. F. Umar, Jorge O. Sofo
Summary: This study presents two models for the atomic structure of inversion domain boundaries in wurzite GaN, one of which has a lower formation energy than a previously proposed model. The newly proposed model, despite having a higher formation energy than the accepted lower-energy structure, can potentially be observed in experiments. By introducing a convenient notation and an improved calculation method, the research provides better estimations of domain wall energies.
Article
Physics, Applied
Shukun Li, Menglai Lei, Rui Lang, Guo Yu, Huanqing Chen, Peijun Wen, Muhammad Saddique Akbar Khan, Linghai Meng, Hua Zong, Shengxiang Jiang, Xiaodong Hu
Summary: Inserting an ultra-thin AlGaN electron blocking layer is a major technique to suppress electron leakage currents in GaN-based blue laser diodes. It has been found that the growth conditions of the upper cladding layers affect the composition of the underlying electron blocking layer and significantly reduce the output performance of LEDs and LDs. By introducing a random walk model, the kinetic influence of cladding layer growth rates on electron blocking layer degradation can be quantitatively clarified.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Peng Wu, Jianping Liu, Lingrong Jiang, Lei Hu, Xiaoyu Ren, Aiqin Tian, Wei Zhou, Masao Ikeda, Hui Yang
Summary: The growth behaviors of GaN on patterned GaN substrate were investigated in this study. Spiral and nucleation growth were observed after the elimination of miscut-induced atomic steps. The morphology of nucleation growth at different temperatures was explained by introducing a multi-nucleation regime with critical supersaturation. Simulated results based on a step motion model successfully elucidated the growth behaviors on stripes. These findings have practical implications for controlling the surface kinetics of devices, such as laser diodes, grown on patterned substrates.
Article
Chemistry, Physical
P. Jaroszynski, K. Sierakowski, R. Jakiela, M. Turek, M. Fijalkowski, T. Sochacki, M. Bockowski
Summary: Manganese diffusion in ion implanted gallium nitride crystals was studied. The manganese ions were implanted into a GaN layer grown on an ammonothermal gallium nitride substrate. After implantation, ultra-high pressure annealing was used to both remove the post-implantation damage and induce the diffusion of manganese ions. Two diffusion mechanisms were observed and the diffusion parameters for each mechanism, including activation energy and temperature-independent diffusion coefficients, were determined. The structural quality of the samples was also evaluated using X-ray diffractometry.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Chemical
Guolong Ni, Shuhuan Wang, Qun Li, Dingguo Zhao, Chunyan Song, Chenxiao Li
Summary: A new technique was developed to prepare Cr17Mn11Mo3N powders with different nitrogen content by controlling atomization pressure and chamber pressure. The synergetic effect between pressures allowed for achieving high nitrogen content, small particle size, narrow size distribution, and high yield of fine powders.
Article
Chemistry, Physical
Inga Kolling, Christoph Hoelzl, Sho Imoto, Serena R. Alfarano, Hendrik Vondracek, Lukas Knake, Federico Sebastiani, Fabio Novelli, Claudius Hoberg, Jean-Blaise Brubach, Pascale Roy, Harald Forbert, Gerhard Schwaab, Dominik Marx, Martina Havenith
Summary: Research shows that under high hydrostatic pressure, TMAO tends to form TMAO·(H2O)4 complexes compared to ambient conditions, accompanied by a weakening of the local hydrogen bond network. With increasing pressure, hydrophobic hydration significantly increases, but levels off at higher pressures.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
I. G. Vasileiadis, L. Lymperakis, A. Adikimenakis, A. Gkotinakos, V Devulapalli, C. H. Liebscher, M. Androulidaki, R. Huebner, Th Karakostas, A. Georgakilas, Ph Komninou, E. Dimakis, G. P. Dimitrakopulos
Summary: By utilizing specific growth conditions, quasi two-dimensional quantum wells with indium contents surpassing 33% can be deposited with an atomic monolayer thickness. The growth mechanism may involve the exchange between indium and gallium atoms, with the highest indium content approaching 50%, indicating potential applications in optoelectronic devices and topological insulators.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
Jian-Kai Xu, Li-Juan Jiang, Qian Wang, Quan Wang, Hong-Ling Xiao, Chun Feng, Wei Li, Xiao-Liang Wang
Summary: By increasing the nitrogen flow and growth temperature, GaN layer can extend more adequately on Si substrate, resulting in improved surface morphology and enhanced crystal quality uniformity. The X-ray diffraction results showed a decrease in GaN (0002) XRD FWHMs from 579 arcsec to around 420 arcsec.
Article
Physics, Applied
M. A. Reshchikov, D. O. Demchenko, D. Ye, O. Andrieiev, M. Vorobiov, K. Grabianska, M. Zajac, P. Nita, M. Iwinska, M. Bockowski, B. McEwen, F. Shahedipour-Sandvik
Summary: Ammonothermal GaN samples were annealed at various temperatures under different N-2 pressure conditions, resulting in the observation of YL2 band and two new PL bands. The origin of YL2 band is attributed to V-Ga-3H(i) complex, while the RL4 band is originated from V-Ga-3O(N) complex.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Multidisciplinary
M. Bockowski, I Grzegory
Summary: The latest advancements and challenges in bulk GaN crystal growth are reviewed and discussed in this article. Fundamental physical barriers hindering the growth process are identified, and the Na-flux, ammonothermal, and halide vapor phase epitaxy methods are presented as the most advanced and promising techniques. The high nitrogen pressure solution approach developed at IHPP PAS is highlighted as a crucial starting point for bulk GaN research.
ACTA PHYSICA POLONICA A
(2022)
Article
Physics, Applied
Qiang Liu, Marcin Zajac, Malgorzata Iwinska, Shuai Wang, Wenrong Zhuang, Michal Bockowski, Xinqiang Wang
Summary: Ethylene is an excellent carbon dopant source for the growth of semi-insulating GaN crystals by halide vapor phase epitaxy, with a doping efficiency much higher than methane. By ethylene doping, a record highest resistivity can be achieved.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Inorganic & Nuclear
Damian Paliwoda, Marco Fabbiani, Melanie Wynn, Frederico Alabarse, Anja Rosenthal, Wilson Crichton, Leszek Konczewicz, Michal Bockowski, David Maurin, Thierry Michel, Umit B. Demirci, Jerome Rouquette, Patrick Hermet, Francesco di Renzo, Arie van der Lee, Guillaume Cassabois, Samuel Bernard, Julien Haines
Summary: Low-dimensional boron nitride chains were successfully synthesized in the pores of siliceous zeolites through a series of steps, and the optimal conditions for this process were determined experimentally. These low-dimensional chains exhibit unique photoluminescence properties.
INORGANIC CHEMISTRY
(2022)
Article
Physics, Applied
Tetsu Kachi, Tetsuo Narita, Hideki Sakurai, Maciej Matys, Keita Kataoka, Kazufumi Hirukawa, Kensuke Sumida, Masahiro Horita, Nobuyuki Ikarashi, Kacper Sierakowski, Michal Bockowski, Jun Suda
Summary: This study investigates the P-type doping in specific areas of gallium nitride (GaN) using magnesium (Mg)-ion implantation and subsequent ultra-high-pressure annealing (UHPA) to enhance the performance of vertical GaN power devices. The research demonstrates that UHPA at lower temperatures can achieve comparable activation of Mg ions and reduce annealing pressure, allowing for larger wafers to be processed. However, controlling the vertical doping profile is challenging. The study also highlights the potential applications of anisotropic diffusion of Mg in vertical device structures.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Leszek Konczewicz, Malgorzata Iwinska, Elzbieta Litwin-Staszewska, Marcin Zajac, Henryk Turski, Michal Bockowski, Dario Schiavon, Mikolaj Chlipala, Sandrine Juillaguet, Sylvie Contreras
Summary: This study presents low-temperature measurements of magnetoresistivity in heavily doped n-type GaN samples obtained through different GaN growth technologies. The samples exhibited negative magnetoresistivity at low temperatures, and the analysis revealed the relationship between the coherence time and temperature.
Article
Chemistry, Physical
Lutz Kirste, Thu Nhi Tran Thi Caliste, Jan L. Weyher, Julita Smalc-Koziorowska, Magdalena A. Zajac, Robert Kucharski, Tomasz Sochacki, Karolina Grabianska, Malgorzata Iwinska, Carsten Detlefs, Andreas N. Danilewsky, Michal Bockowski, Jose Baruchel
Summary: In this paper, a new type of extended defect in ammonothermally grown gallium nitride (GaN) single crystals, called hexagonal honeycomb shaped dislocation bundles, is investigated using X-ray Bragg diffraction imaging and defect selective etching. These dislocation bundles are either grouped in specific areas to form limited subgrain boundaries or aligned in straight long chains. The lattice distortions associated with these dislocation bundles are extensively measured to provide clues about their origin.
Article
Chemistry, Multidisciplinary
Aleksander Szpakiewicz-Szatan, Szymon Starzonek, Tomasz K. Pietrzak, Jerzy E. Garbarczyk, Sylwester J. Rzoska, Michal Bockowski
Summary: A new nanocomposite material was synthesized from glass of NaFePO4 composition using high pressure processing. The sample's thermal, structural, electrical, and dielectric properties were characterized by DTA, XRD, and BDS techniques. The high-pressure-high-temperature treatment significantly increased the electrical conductivity by two orders of magnitude compared to the initial glass, and this effect was stronger than the lithium analogue. This enhancement was attributed to enhanced electron hopping in the pressure-treated samples according to Mott's theory. The nanocrystalline composite consisted of NASICON and alluaudite phases, which could serve as potential cathode materials for Na batteries.
Article
Materials Science, Ceramics
Szymon Starzonek, Aleksander Szpakiewicz-Szatan, Sylwester J. Rzoska, Aleksandra Drozd-Rzoska, Michal Bockowski, Tomasz K. Pietrzak, Jerzy E. Garbarczyk
Summary: This paper investigates systems formed in a solid glassy state after a nanocrystallization process above the glass temperature. It analyzes the electric conductivity and relaxation processes after treatment under high temperature and high pressure. The results show an increase in density, electric conductivity, and qualitative changes in dynamics processes. The paper also introduces a new method for data analysis based on the activation and critical-like nature of processes. It provides evidence of pressure evolution of the glass and crystallization temperatures, indicating the unique possibility of maxima and crossovers.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Physics, Condensed Matter
Igor Prozheev, Malgorzata Iwinska, Tomasz Sochacki, Michal Bockowski, Rene Bes, Filip Tuomisto
Summary: The results of positron lifetime and X-ray absorption spectroscopy in Si-doped GaN crystals, grown by HVPE, are presented. High Si concentration leads to significant compensation effects. Ga vacancies are insufficient as compensation centers and other acceptor-like impurities are present at much lower concentrations than Si. X-ray absorption shows that the local environment of Si dopants is different in compensated samples. Simulated spectra suggest that Si has a higher presence in the nearest local environment in compensated spectra, indicating autocompensation of Si dopants in high Si content GaN samples grown by HVPE.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Emi Kano, Ritsuo Otsuki, Koki Kobayashi, Keita Kataoka, Kacper Sierakowski, Michal Bockowski, Masahiro Nagao, Tetsuo Narita, Tetsu Kachi, Nobuyuki Ikarashi
Summary: Transmission electron microscopy is used to observe dislocation loops in Mg-ion-implanted GaN during annealing. The diffusion of native defects is slowed down at higher pressure during annealing. Secondary ion mass spectrometry shows that annealing at higher pressure retards the migration of Mg and increases its concentration in the ion-implanted region. These findings provide a design principle for the annealing process to activate ion-implanted Mg in GaN.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Chemistry, Physical
Tomasz Sochacki, Robert Kucharski, Karolina Grabianska, Jan L. L. Weyher, Magdalena A. A. Zajac, Malgorzata Iwinska, Lutz Kirste, Michal Bockowski
Summary: A detailed analysis was conducted on the morphology of gallium nitride crystal growth obtained by ammonothermal and halide vapor phase epitaxy methods. The study aimed to determine the source of triangular planar defects visible in X-ray topography as areas with locally different lattice parameters. It was found that these defects are related to growth hillocks, and particular attention was paid to analyzing the merging of hillocks and its consequences. The nature and cause of these defects were determined, with the angle formed between adjacent hillocks being identified as a key factor.
Review
Physics, Applied
Maciej Matys, Kazuki Kitagawa, Tetsuo Narita, Tsutomu Uesugi, Michal Bockowski, Jun Suda, Tetsu Kachi
Summary: This review briefly summarizes the major challenges and recent progress in the development of GaN Junction Barrier Schottky (JBS) diodes using selective-area p-type doping with ion implantation and ultra high-pressure annealing (UHPA) process. The high-performance JBS diodes demonstrated superior electrical characteristics and nondestructive breakdown.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Yuki Hatakeyama, Tetsuo Narita, Michal Bockowski, Tetsu Kachi, Masamichi Akazawa
Summary: The gap states near the conduction band edge in Mg-ion-implanted GaN and Al2O3 interface were investigated, and the gap state density can be improved through capless ultra-high-pressure annealing.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
M. A. Reshchikov, D. O. Demchenko, M. Vorobiov, O. Andrieiev, B. McEwen, F. Shahedipour-Sandvik, K. Sierakowski, P. Jaroszynski, M. Bockowski
Summary: The Ca-Ga acceptor in GaN was studied using experiments and calculations. The acceptor is responsible for the green luminescence band in GaN. The capture coefficients for electrons and holes were obtained from the experiments. The presence of Ca as a common contaminant affects the radiative recombination in GaN samples.
