Growth of Ga0.70In0.30N/GaN Quantum-Wells on a ScAlMgO4 (0001) Substrate with an Ex-Situ Sputtered-AlN Buffer Layer

• Published in: Materials Vol. 17; no. 1; p. 167
• Main Authors: Zheng, Dong-Guang, Min, Sangjin, Kim, Jiwon, Han, Dong-Pyo
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.01.2024; MDPI
• Subjects: Aluminum nitride; Annealing; Buffer layers; Crystal dislocations; Crystallinity; Crystallography; Dislocation density; Gallium nitrides; Light emitting diodes; Low temperature; metalorganic vapor phase epitaxy; mixed-type dislocation; Morphology; Photoluminescence; Quantum efficiency; Quantum wells; R&D; Research & development; Sapphire; ScAlMgO4 substrate; screw-type dislocation; Semiconductors; Spectral emittance; sputtered-AlN buffer layer; Substrates; Temperature; Temperature dependence
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17010167

This study attempted to improve the internal quantum efficiency (IQE) of 580 nm emitting Ga0.70In0.30N/GaN quantum-wells (QWs) through the replacement of a conventional c-sapphire substrate and an in-situ low-temperature GaN (LT-GaN) buffer layer with the ScAlMgO4 (0001) (SCAM) substrate and an ex-situ sputtered-AlN (sp-AlN) buffer layer, simultaneously. To this end, we initially tried to optimize the thickness of the sp-AlN buffer layer by investigating the properties/qualities of an undoped-GaN (u-GaN) template layer grown on the SCAM substrate with the sp-AlN buffer layer in terms of surface morphology, crystallographic orientation, and dislocation type/density. The experimental results showed that the crystallinity of the u-GaN layer grown on the SCAM substrate with the 30 nm thick sp-AlN buffer layer [GaN/sp-AlN(30 nm)/SCAM] was superior to that of the conventional u-GaN template layer grown on the c-sapphire substrate with an LT-GaN buffer layer (GaN/LT-GaN/FSS). Notably, the experimental results showed that the structural properties and crystallinity of GaN/sp-AlN(30 nm)/SCAM were considerably different from those of GaN/LT-GaN/FSS. Specifically, the edge-type dislocation density was approximately two orders of magnitude higher than the screw-/mixed-type dislocation density, i.e., the generation of screw-/mixed-type dislocation was suppressed through the replacement, unlike that of the GaN/LT-GaN/FSS. Next, to investigate the effect of replacement on the subsequent QW active layers, 580 nm emitting Ga0.70In0.30N/GaN QWs were grown on the u-GaN template layers. The IQEs of the samples were measured by means of temperature-dependent photoluminescence efficiency, and the results showed that the replacement improved the IQE at 300 K by approximately 1.8 times. We believe that the samples fabricated and described in the present study can provide a greater insight into future research directions for III-nitride light-emitting devices operating in yellow–red spectral regions.