Electrical Characteristics of Surface Stoichiometry Controlled p-GaN Schottky Contacts

摘要

Experimental results of electrical characteristics of Au/Ni Schottky contacts formed on three kinds of p-GaN layers, which were grown at different turn-off temperatures (300, 600, and 900℃) of an NH_3 gas supply (T_(NH_3)) on cooling down at the end of the growth to control the surface stoichiometry. In the internal photoemission results, the Schottky barrier heights of all the samples were as high as around 2.2 eV, and a slight increase by 0.1 eV was observed when the T_(NH_3) decreased from 900 to 300℃. At the same time, carrier capture and emission from accepter-like mid-gap level defects decreased as the T_(nh_3) decrease. The N-rich cooling-down condition tends to passivate the acceptor type defects or create donor type defects for the compensation, and the pinning position at the interface might be moved to the conduction band edge slightly.