Properties and modification of native oxides of InP(100)

Abstract

Abstract Properties of oxidized InP surfaces, which are known to cause less electrical and optical losses than other III–V oxides, are relevant to develop the passivation of current and future applications of III–V crystals (e.g. lasers, detectors). We report that a proper low-temperature (LT) (<400 °C) gas exposure with NH3 or O2 enables beneficial modifications of InP native oxides, of which formation is difficult to avoid in devices. Effects of the gas exposure depend on the doping of InP. NH3 exposure without a plasma source at 250 °C or lower temperature increases photoluminescence (PL) intensity of native-oxide covered n-InP crystals, which interestingly provide a stronger PL signal than n-InP with the HCl-cleaned surface. In contrast, O2 exposure around 300 °C increases PL signal of native-oxide covered p-type InP. Core-level photoelectron spectra reveal that N atoms are incorporated into the native oxide system of InPO4/InP during LT NH3 exposures. Scanning tunneling microscopy shows a band bending and a tendency to crystallization at native-oxide covered InP surfaces. Photoelectron spectra, which are analyzed with recent calculations, show larger variation in the bonding environment for the host In atoms and for incorporated N atoms, as compared to the P bonding sites in the InPO4 native oxide.