Evaluation of plasma and thermal sources for atomic hydrogen-assisted epitaxy of InP

Homoepitaxial layers of InP have been grown on (100) InP substrates by gas source molecular beam epitaxy while simultaneously exposed to an atomic hydrogen flux produced either by plasma or by thermal cracking. The thermal H-assisted growths were performed with various H fluxes, H2 cracker cell temperatures, PH3 cracker cell temperatures, annealing conditions, and Be doping levels. Photoluminescence and Hall effect studies indicate improved optical and electrical properties of the InP layers grown in the presence of H as compared to layers grown by conventional epitaxy without H. This improvement is attributed to a reduction in point defects due to the removal of unwanted phosphine cracker products, such as P4, from the sample surface during growth by reaction with H. The reconstructed 2×1 H-terminated surface may also reduce P vacancy defects due to the absence of the missing phosphorus dimer row present on the conventional 2×4 surface. Problems associated with donor impurity contamination, which increased with thermal source temperature, were avoided by use of the plasma source.