Smalc-Koziorowska Julita, Grzanka Ewa, Lachowski Artur, Hrytsak Roman, Grabowski Mikolaj, Grzanka Szymon, Kret Slawomir, Czernecki Robert, Turski Henryk, Marona Lucja, Markurt Toni, Schulz Tobias, Albrecht Martin, Leszczynski Mike
Institute of High Pressure Physics PAS, Sokołowska 29/37, 01-142 Warsaw, Poland.
Department of Materials Science, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw, Poland.
ACS Appl Mater Interfaces. 2021 Feb 17;13(6):7476-7484. doi: 10.1021/acsami.0c21293. Epub 2021 Feb 2.
In this work, we study the thermal degradation of In-rich InGaN quantum wells (QWs) and propose explanation of its origin based on the diffusion of metal vacancies. The structural transformation of the InGaN QWs is initiated by the formation of small initial voids created due to agglomeration of metal vacancies diffusing from the layers beneath the QW. The presence of voids in the QW relaxes the mismatch stress in the vicinity of the void and drives In atoms to diffuse to the relaxed void surroundings. The void walls enriched in In atoms are prone for thermal decomposition, what leads to a subsequent disintegration of the surrounding lattice. The phases observed in the degraded areas of QWs contain voids partly filled with crystalline In and amorphous material, surrounded by the rim of high In-content InGaN or pure InN; the remaining QW between the voids contains residual amount of In. In the case of the InGaN QWs deposited on the GaN layer doped to n-type or on unintentionally doped GaN, we observe a preferential degradation of the first grown QW, while doping of the underlying GaN layer with Mg prevents the degradation of the closest InGaN QW. The reduction in the metal vacancy concentration in the InGaN QWs and their surroundings is crucial for making them more resistant to thermal degradation.
在这项工作中，我们研究了富铟InGaN量子阱（QW）的热降解，并基于金属空位的扩散对其起源提出了解释。InGaN量子阱的结构转变是由量子阱下方层中扩散而来的金属空位团聚形成的小初始空洞引发的。量子阱中存在的空洞缓解了空洞附近的失配应力，并驱使铟原子扩散到松弛的空洞周围。富含铟原子的空洞壁易于热分解，这导致周围晶格随后解体。在量子阱退化区域观察到的相包含部分填充有结晶铟和非晶材料的空洞，周围是高铟含量的InGaN或纯InN边缘；空洞之间剩余的量子阱含有残余量的铟。在沉积在n型掺杂的GaN层或非故意掺杂的GaN上的InGaN量子阱的情况下，我们观察到第一个生长的量子阱优先退化，而用Mg掺杂底层GaN层可防止最接近的InGaN量子阱退化。降低InGaN量子阱及其周围环境中的金属空位浓度对于使其更耐热降解至关重要。
