High mobility conducting channel at semi-insulating GaAs-metal oxide interfaces

The absence of an efficient technology of GaAs passivation limits the use of III-V semiconductors in modern electronics. The effect reported here can possibly lead to a solution to this long standing problem. We found that an electrically conducting interfacial channel is formed when insulating metal oxide dielectrics are deposited on untreated semi-insulating GaAs wafers by reactive RF sputtering in argon/oxygen plasma. The conducting channel is n-type with a surface charge density of 107-1010 cm-2 and Hall mobility as high as 6000 cm2/V s, depending on the RF plasma excitation power and the oxygen content during deposition. The conducting channel is formed by depositing any of the tested metal oxide dielectrics: MgO, SiO2, Al2O3, and HfO2.