GROWTH MECHANISMS OF III-V COMPOUNDS BY ATOMIC HYDROGEN-ASSISTED EPITAXY

Epitaxial layers of InP and InGaAsP have been grown on (1 0 0) InP sub strates by gas source molecular beam epitaxy while simultaneously expo sed to an atomic hydrogen flux produced by a thermal cracker. Transmis sion electron microscopy and photoluminescence studies indicate improv ed structural and optical properties of the InGaAsP layers, while Hall effect measurements indicate no degradation in the electrical propert ies, as compared to layers grown by conventional epitaxy without hydro gen. This improvement is attributed to a reduction in lateral composit ion modulation (LCM), which develops at the surface of the InGaAsP lay ers during growth due to the existence of a miscibility gap. A detaile d atomistic model, including surface reconstruction effects based on r eflection high energy electron diffraction observations, is developed to explain the growth processes occurring on H-exposed (1 0 0) III-V s urfaces. A simple rate equation model is used to understand the reduct ion in LCM in terms of a decreased surface diffusion length of adatoms in the presence of H. (C) 1998 Elsevier Science B.V. All rights reser ved.