Preventing phase separation in MOCVD-grown InAlAs compositionally graded buffer on silicon substrate using InGaAs interlayers

• Published in: Journal of crystal growth 2017-11, Vol.478, p.64-70
• Main Authors: Kohen, David, Nguyen, Xuan Sang, Made, Riko I., Heidelberger, Christopher, Lee, Kwang Hong, Lee, Kenneth Eng Kian, Fitzgerald, Eugene A.
• Format: Article
• Language: English
• Subjects: A1. Defects; A3. Metalorganic chemical vapor deposition; A3. Metalorganic vapor phase epitaxy; B2. Semiconducting III–V materials; B2. Semiconducting ternary compounds; Buffers; Chemical vapor deposition; Dislocation density; Evaluation; Gallium arsenide; Indium aluminum arsenides; Interlayers; Metalorganic chemical vapor deposition; Phase separation; Silicon; Silicon substrates; Studies; Surface roughness
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2017.08.025

•Compositionally graded InAlAs buffers are grown on Ge-on-Silicon substrates.•Final composition of the InAlAs buffer is 60% [In].•Phase separation in the InAlAs compositionally graded buffer is prevented using InGaAs interlayers.•InP virtual substrates with TDD around 1×108/cm2 is demonstrated. Compositionally graded InAlAs buffers grown by metal–organic chemical vapor deposition are impaired by phase separation occurring at In content higher than 35%. Phase separation results in rough epilayers with poor crystalline material quality. By introducing low temperature grown InGaAs interlayers in the compositionally graded InAlAs buffer, the surface roughness decreases, allowing a grading of up to In0.60Al0.40As without any phase separation occurring. This composite buffer is applied to fabricate a 200mm diameter InP-on-Si virtual substrate with a threading dislocation density around 1×108cm−2.