Reactive Ion Etching for Improved Ohmics in AlGaN/GaN HEMT's

PRE-METAL-DEPOSITION ion etching is a widely used technique for improving metal to semiconductor contact resistivity in n-type GaN. The application of pre-metal-deposition ion etching to AlGaN/GaN heterostructures is more critical since an over-etch of the AlGaN layer would imply the removal of the 2DEG with consequent loss of charge, reduction of tunnelling current, and degradation of contact resistance. In the present study a medium power Cl2 reactive ion etching (RIE) was applied to Al0.3Ga0.7N/AlN/GaN heterostructure for improving metal contact resistance.