Interface Charge Engineering for Enhancement-Mode GaN MISHEMTs

We demonstrate an efficient approach to engineer the dielectric/AlGaN positive interface fixed charges by oxygen plasma and post-metallization anneal. Significant suppression of interface fixed charges from 2 × 10
¹³
to 8 × 10
¹²
cm
^-2
was observed. Experimental and theoretical electron mobility characteristics and the impact of remote impurity scattering were investigated. The reduction in oxide/semiconductor interface charge density leads to an increase of electron mobility, and enables a positive threshold voltage.