Current Drops in CF4 Plasma-Treated AlGaN/GaN Heterojunction in Polar Gas Ambient

This letter reports the phenomenon of current drops in an AlGaN/GaN heterojunction with CF4 plasma treated in a polar gas ambient. Ungated AlGaN/GaN HEMT with CF4 plasma treatment was tested in ethanol, acetonitrile, and an acetic acid gas ambient, and the current dropped by 52%, 51% and 61%, respectively, which are much higher than the drops (6%, 7%, and 8%) in normal ungated HEMT. On the one hand, based on “ambient doping”, a possible model was proposed to explain this phenomenon. On the other hand, the lower initial current was very important to increase the sensitivity. This means that the initial current should be elaborately designed to achieve maximum sensitivity.