Properties and modification of native oxides of InP(100)

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 degrees C) gas exposure with NH3 or O-2 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 degrees 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, O-2 exposure around 300 degrees 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.

Automated summary

Properties of oxidized InP surfaces are important for developing passivation of III-V crystals. Exposure to NH3 or O-2 gas at low temperatures can modify InP native oxides. NH3 exposure increases photoluminescence intensity for n-InP crystals with native oxide, while O-2 exposure increases it for p-type InP crystals.