Paper SS+AS+NS-ThA3
Evolution of Surface-Assisted Oxidation of GaAs by Gas-Phase N₂O, NO and O₂

Thursday, November 13, 2014, 3:00 pm, Room 309

Interests in metal-insulator-semiconductor field effect transistors (MISFETs) have been re-ignited recently due to the approaching of the scaling limit of Si complementary metal-oxide-semiconductors (CMOS). The fate of the III-V semiconductors relies strongly on the availability of a suitable surface passivation technology for fabrication of high quality insulator/III-V semiconductor interface. Gallium oxides on GaAs represent one of contenders for suitable surface passivated oxide-based dielectrics that could produce device-quality electrical interfaces between the oxide and semiconductor. However, there has been a debate on possible GaAs oxidation mechanisms over years. A comparisonal study between O₂ and other reactive but heteronuclear molecules (such as NO and N₂O) near realistic conditions would provide new insights for a better understanding of the GaAs oxidation process.

A near-ambient pressure X-ray photoelectron spectroscopy (NAP XPS) study of interfacial chemistry between GaAs (100) and three oxidizing gases, N₂O, NO and O₂, are carried out in a wide range of pressures and temperatures. At room temperature, surface oxidation, involving the formation of both Ga₂O and Ga₂O₃ is observed with the extent of oxidation in the order of NO>O₂>N₂O at elevated pressures. At elevated temperatures, the extent of oxidation is in the order of O₂> NO >N₂O. Our experimental results show that the oxidation of GaAs (100) by N₂O and NO is primarily determined by the probability and nature of interactions at the gas/semiconductor interface, whereas the limiting factor in the case of O₂ is the energy requirement for O-O bond dissociation.