Hydrogenation of InP by Phosphine Plasma

Hydrogenation of an InP surface has been attempted by the glow discharge of phosphine (PH3) gas diluted with Ar. Atomic P in the PH3 plasma is effective in suppressing the preferential etching of P at the InP surface which occurs easily by the exposure to the H2 plasma. The mirror surface of InP is found to be maintained after the plasma exposure even at 250°C. It is verified by secondary ion mass spectroscopy analysis that H atoms with a density higher than 1×1018 cm-3 diffuse into the bulk InP to 500 nm in depth. An enhancement of the photoluminescence (PL) intensity occurs on the hydrogenated surface, and a complete recovery of the PL intensity is observed after annealing at 350°C for 3 min. In the case of exposure to the PH3 and H2 mixture plasma, an increase of the H2 flow rate leads to further enhancement of the PL intensity which is attributed to the band bending at the surface due to an introduction of P vacancies.