Optimization of InAlAs buffers for growth of GaAs-based high indium content InGaAs photodetectors

• Published in: Journal of crystal growth 2015-09, Vol.425, p.346-350
• Main Authors: Chen, X.Y., Gu, Y., Zhang, Y.G., Xi, S.P., Guo, Z.X., Zhou, L., Li, A.Z., Li, Hsby
• Format: Article
• Language: English
• Subjects: A1: Metamorphic buffer; A3: Molecular beam epitaxy; B1: InGaAs; B3: Photodetector; Buffers; Gallium arsenide; Gallium arsenides; Indium; Lattices; Molecular structure; Nucleation; Photodetectors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2015.02.102

The impact of buffer schemes on the strain relaxation and structural characteristics of In0.83Ga0.17As photodetector structures with relatively high lattice mismatch (5.9%) grown on GaAs substrate by gas source molecular beam epitaxy has been investigated. Reduction of surface roughness, full widths at half maximum of X-ray diffraction signals and threading dislocations, as well as an enhancement of photoluminescence intensity were observed for the In0.83Ga0.17As photodetector structure with fixed-composition In0.83Al0.17As buffer compared to those with continuously graded InxAl1−xAs buffer. The role of fixed-composition In0.83Al0.17As buffer layer is investigated, and it is believed that a couple monolayers of In0.83Al0.17As at the initial growth stage can provide high density of nucleation site by the formation of quantum dots at the interface and thus to reduce the strain energy caused by the large lattice mismatch between In0.83Al0.17As and GaAs. •GaAs-based In0.83Ga0.17As photodetectors on different buffers were grown by GSMBE.•Material qualities were improved by fixed-composition In0.83Al0.17As buffer.•Characteristics were further ameliorated by inserting InAs QDs at the interface.•The dislocation generation mechanism of different buffers was analyzed.