Analysis of indium nitride surface oxidation

Abstract

InN is a III–V semiconductor with a wide band gap of 1.89 eV and mobility of 2700 cm2 V−1 s−1 (300 K) which has applications in optoelectronics. As with GaAs, surface oxidation and degradation after aging in air is a problem that must be taken into account during device fabrication. Of the possible techniques, x-ray photoelectron spectroscopy was used as it could detect nitrogen, while the x-ray beam did not preferentially sputter nitrogen as rapidly as other techniques. Various sample preparation techniques and sputter etching with xenon were used to avoid nitrogen depletion as well as to view initial chemisorption of oxygen onto InN surfaces. We found the surface oxidation of InN was clearly dependent on the aging and sample treatment history. The first stage of oxidation is the bonding of oxygen onto nitrogen to form an In–NO complex. After sputter etching or abrasive cleaning, the In–NO complex further oxidized to form an In–NO2 complex. The final oxidation state after aging was found to be dependent on the sample preparation conditions. Finally, the In(3d5/3) Auger parameter plots indicate that the indium is predominantly bonded to nitrogen regardless of the aging and sample treatment. These results correspond closely to studies on GaAs where during the oxidation process, oxygen chemisorbs onto the metalloid.