Sulfide‐assisted reordering at the InP surface and SiNx/InP interface

Abstract

The structural and chemical changes induced by the annealing of InP which has been exposed to gas‐phase polysulfide, a known passivation method for the reduction of surface states for InP, were investigated using in situ low‐energy electron diffraction (LEED), thermal desorption spectrometry, and x‐ray photoelectron spectroscopy (XPS). A diffused InP (1×1) LEED pattern was observed on InP which had been exposed to ultraviolet/O3 followed by etching with a 1:30 HF solution. The (1×1) LEED pattern became sharper after the gas‐phase polysulfide exposure and the subsequent annealing. The sharpest pattern was obtained after annealing at 400 °C. Accompanying these structural changes were the desorptions of species containing H and S at 300 °C and the species containing H, S, and P at 400 °C. XPS analyses showed that during the structural changes, the multiple sulfide species on the as‐exposed surface were converted to a single relatively stable In–S species as a result of appropriate annealing. Similar chemical changes of sulfide species were obtained at the SiNx/InP interface. The results suggest that sulfide assisted the reordering of the InP surface, thus leading to the reduction in interface state densities which were determined by capacitance–voltage measurements.