Properties and thermal stability of the SiO₂/GaAs interface with different surface treatments

High quality SiO2 films were deposited by plasma-enhanced chemical vapor deposition on GaAs wafers which received different surface treatments. It was found that metal-oxide-semiconductor (MOS) capacitors which received surface nitridation were unstable under high-temperature anneal (600°C). These instabilities are interpreted in terms of free As precipitates at the interface. When, instead, a thin Si layer was deposited on the GaAs surface, stable interfaces were obtained at 600°C. These MOS capacitors appear to show both deep depletion and inversion.