Ohmic contacts on n-type layers formed in GaN/AlGaN/GaN by dual-energy Si ion implantation

Electrical properties of Si-implanted n-type GaN/AlGaN/GaN layers and contact resistances of ohmic electrodes (TiAl) formed on these layers have been examined. Experimental results have clearly shown that ohmic electrodes with a low specific-contact resistance of 1.4 × 10−7 Ω cm2 can be fabricated on the n-type layer having a low sheet resistance of 145 Ω/sq, which has been formed by the dual-energy Si ion implantation (80 keV:1.01 × 1015/cm2 + 30 keV:1.6 × 1014/cm2) and subsequent annealing at 1200 °C for 2 min using a Si3N4 layer as an encapsulant.