Comparative Analysis of Ni/Ag and Ni/Au Contacts on GaN/AlGaN/GaN Platform

Herein, the electrical characteristics and Schottky barrier of Ni/Au and Ni/Ag contacts on the GaN/AlGaN/GaN heterojunction are investigated. Both contacts on the p‐GaN contact layer (Mg: ≈3 × 10 19 cm −3 ) exhibit weak Schottky characteristics. The nonlinear current–voltage ( I – V ) characteristics are observed, leading to variations in contact resistance ( R C ) and sheet resistance ( R sh ) with changing bias voltage. The Ni/Ag contact achieves a lower Schottky barrier height calculated by using the I – V method. Furthermore, when employing a p ++ ‐GaN layer (Mg: ≈1 × 10 20 cm −3 ) as the contact layer, the Ni/Ag contact forms an Ohmic contact without Schottky characteristics, achieving a satisfactory R C of 30.31 Ω mm. This result demonstrates its viability as a competitive candidate for p‐channel field‐effect transistors’ fabrication.