Quality improvement of oxidized-GaAs/n-GaAs structure by nitrogen plasma treatment

A low surface/interface state density and a high quality nm-thickness insulating layer is necessary for an ultra-high-speed metal/insulator/semiconductor (MIS) type compound semiconductor device. However, such an ultra-thin insulator with good interface quality is not available yet. The authors reported that direct oxidation of a GaAs surface by UV and ozone can form a controlled nm-thin insulating layer and it suppresses leakage current, although the process deteriorates the IS interface characteristics. They also demonstrated performances and problems of GaAs MISFETs which have nm-thin oxidized-GaAs as the insulating layer. Hara et al. (1999) reported improved C-V characteristics of a nitrogen plasma treated oxidized GaAs surface. The authors investigated effects of nitrogen plasma treatment upon oxidized and non oxidized [100] n-GaAs wafers, and confirmed improved quality of the oxidized wafers by the nitrogen plasma treatment.