GaAs metal-oxide-semiconductor device with HfO₂/TaN gate stack and thermal nitridation surface passivation

Oxides induced Fermi level pinning at the interface between the GaAs and high-k gate dielectric is a major obstacle for developing high performance GaAs metal-oxide-semiconductor (MOS) devices. In this letter, thermal nitridation treatment on GaAs surface prior to the high-k deposition is proposed to solve the issue of interface pinning. It is found that an optimized nitride layer formed during the thermal nitridation surface treatment can effectively suppress the oxides formation and minimize the Fermi level pinning at the interface between the GaAs and HfO₂. By using thermal nitridation treatment and in situ metal-organic chemical vapor deposition HfO₂ as high-k gate dielectric, GaAs MOS capacitor with improved capacitance-voltage characteristics and reduced gate leakage current is achieved.