Improvement of ohmic contact to P-type GaN using two-step activation processing

Abstract

A two-step rapid thermal annealing (RTA) process was investigated for electrical activation of magnesium doped GaN layer. The samples were studied by room temperature Hall measurements and I-V curve. In the two-step RTA process, the first low temperature step (600°C) with a long annealing time (4 min) was followed by the second high temperature (850°C) step with a short annealing time. A hole concentration of 1. 39 × 10 18 cm -3 was achieved for the activated sample. And the specific contact resistance for Ni/Au-contacted p-GaN was determined to be 1.8×10 -4 Ω.cm 2 , These results show that the two-step RTA process significantly improves the electrical properties of P-GaN layer compared to the one-step RTA process.