Low-resistance electrical contacts to p-type GaN by using In{sub}xGa{sub}(1-x)N cap layers

摘要

A novel type of low-resistance ohmic contacts is demonstrated utilizing polarization-induced electric fields in thin p-type InGaN layers on p-type GaN. An increase of the hole tunneling probability through the barrier and a concomitant significant decrease of the specific contact resistance can be attributed to a reduction of the tunneling barrier width in the InGaN capping layers due to the polarization-induced electric fields. The specific contact resistance of Ni (10 nm)/Au (30 nm) contacts deposited on the InGaN capping layers was determined by the transmission line method. Specific contact resistances of 1.2 × 10{sup}(-2) Ωcm{sup}2 and 6×10{sup}(-3) cm{sup}2 were obtained for capping layer thicknesses of 20 nm and 2 nm, respectively.