Strain-induced compositional shift in the growth of InAsyP1-y onto (100) InP by gas-source molecular beam epitaxy

C. QUI; R. V. KRUZELECKY; D. A. THOMPSON; D. COMEDI; G. BALCAITIS; B. J. ROBINSON; R. W. STREATER

CANADIAN JOURNAL OF PHYSICS

Año: 1992 vol. 70 p. 886 - 892

0008-4204

The growth of InAsxP1-x onto (100) InP by gas-source molecular beam epitaxy was examined systematically, focusing on control of the resulting As/P incorporation ratio. The group V fluxes were obtained by passing phosphine and arsine through a dual-input low-pressure gas cracker. For a given flow ratio of the source gases, the arsenic fraction y of the resulting InAsxP1-x films is seen to increase with the film thickness over the first 1500 angstrom (1 angstrom = 10(-10) m) as indicated by secondary ion mass spectroscopy. Auger depth profiling and by Rutherford backscattering spectroscopy. Thin, strained InAsyP1-y layers (0.30 < y < 0.70, corresponding to a compressive strain of about 1.0-2.2%) contain about 5-20% less As than similarly grown thicker. relaxed layers. For a given growth rate and substrate temperature. the relative compositional shift is found to be linearly proportional to the effective strain corresponding to y. Substrate temperatures above 475-degrees-C further reduce the incorporation ratio of As into both strained and relaxed InAsyP1-y layers. initially enhancing the strain-induced compositional shift. However, strain minimization via a compositional shift competes with a greater rate of relaxation of the InAsP lattice with film thickness at higher substrate temperatures.