Air-gap capacitance-Voltage analysis of p-InP surfaces

A novel air-gap capacitance-Voltage (C-V) method is introduced. This method is powerful tool for characterizing electrical properties of "free" or ultrathin-insulator-covered surfaces for III-V semiconductors. Air-gap C-V characteristics of p-InP surfaces with and without natural oxide are reported for the first time. Unexpectedly, the surface with natural oxide gives relatively low-density surface states. Surfaces covered with ultrathin Al2O3 film were also measured, indicating the importance for further investigation and optimization of surface process.