Graded-composition buffer layers using digital AlGaAsSb alloys
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
We describe step-graded digital-alloy buffers using alternate layers of Al{sub 0.5}Ga{sub 0.5}As and Al{sub 0.5}Ga{sub 0.5}As{sub 0.65}Sb{sub 0.35} grown on GaAs substrates by molecular beam epitaxy. The buffers consist of three sets of superlattices with AlGaAs/AlGaAsSb layer thicknesses of 7.7/2.3 nm, 5.4/4.6 nm, and 3.1/6.9 nm, respectively, terminating in a lattice constant equal to that of bulk In{sub 0.32}Ga{sub 0.68}As. Transmission electron micrographs show that most of the misfit-generated dislocations lie near the steps in pseudoalloy composition, and atomic force micrographs indicate a rms surface roughness of 3.6 nm. A 20.5-period lattice-matched InGaAs/InAlAs reflector stack grown on such a buffer has a peak reflectivity of 98% near 1.3 {mu}m. These buffers provide potentially useful substrates for optoelectronic device applications near 1.3 {mu}m using strained InGaAs active regions. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 118385
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 16 Vol. 67; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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