Improved interfacial properties of GaAs MOS capacitor with NH3-plasma-treated ZnON as interfacial passivation layer**Project supported by the National Natural Science Foundation of China (Nos. 61176100, 61274112, 61404055).

Abstract

The GaAs MOS capacitor was fabricated with HfTiON as high-k gate dielectric and NH3-plasma-treated ZnON as interfacial passivation layer (IPL), and its interfacial and electrical properties are investigated compared to its counterparts with ZnON IPL but no NH3-plasma treatment and without ZnON IPL and no plasma treatment. Experimental results show that low interface-state density near midgap (1.17 × 1012 cm−2 eV−1) and small gate leakage current density have been achieved for the GaAs MOS device with the stacked gate dielectric of HfTiON/ZnON plus NH3-plasma treatment. These improvements could be ascribed to the fact that the ZnON IPL can effectively block in-diffusion of oxygen atoms and out-diffusion of Ga and As atoms, and the NH3-plasma treatment can provide not only N atoms but also H atoms and NH radicals, which is greatly beneficial to removal of defective Ga/As oxides and As-As band, giving a high-quality ZnON/GaAs interface.