A secret luminescence killer in deepest QWs of InGaN/GaN multiple quantum well structures

• Published in: Journal of crystal growth Vol. 536; p. 125579
• Main Authors: Hospodková, A., Hájek, F., Pangrác, J., Slavická Zíková, M., Hubáček, T., Kuldová, K., Oswald, J., Vaněk, T., Vetushka, A., Čížek, J., Liedke, M.O., Butterling, M., Wagner, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2020; Elsevier BV
• Subjects: A1. Defects; A1. Impurities; A3. Metalorganic vapor phase epitaxy; A3. Quantum wells; B1. Nitrides; Buffer layers; Diffusion layers; Gallium nitrides; Hydrogen atoms; Indium gallium nitrides; Luminescence; Photoluminescence; Positron annihilation; Quantum wells; Radiative recombination; Vacancies; A3. Quantum wells; A3. Metalorganic vapor phase epitaxy; A1. Impurities; B1. Nitrides; A1. Defects
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2020.125579

•Alternative explanation of non-radiative recombination in deepest QWs is suggested.•Non-radiative recombination is caused by VGa-nH complexes in InGaN layers.•Trapping of diffusing VGa from GaN buffer in strained InGaN is supposed.•Combination of SIMS, PL and VESPAS measurement is strong tool to study defects.•VGa seems to be responsible for 3x2 CCS reactor PL radial inhomogeneity. This work suggests new alternative explanation why a single InGaN quantum well (QW) or the deepest QWs in the multiple quantum well (MQW) structures suffer with a high non-radiative recombination rate. According to SIMS results, positron annihilation spectroscopy and photoluminescence measurements we suggest that vacancy of Ga in complex with hydrogen atoms can play a dominant role in non-radiative Shockley-Read-Hall recombination of the deepest QWs in InGaN/GaN MQW structures. Vacancy of gallium originate dominantly in GaN buffer layers grown at higher temperatures in H2 atmosphere and are transported to the InGaN/GaN MQW region by diffusion, where they are very effectively trapped in InGaN layers and form complex defects with hydrogen atoms during epitaxy of InGaN layers. Trapping of gallium vacancies is another suggested mechanism explaining why the widely used In containing prelayers help to increase the luminescence efficiency of the InGaN/GaN MQW active region grown above them. Understanding the mechanism why the luminescence efficiency is suppressed in deeper QWs may be very important for LED community and can help to develop new improved technologies for the growth of InGaN/GaN MQW active region.