Schottky barrier height engineering in vertical p-type GaN Schottky barrier diodes for high-temperature operation up to 800 K

Abstract

We have fabricated vertical p-type gallium nitride (GaN) Schottky barrier diodes (SBDs) using various Schottky metals such as Pt, Pd, Ni, Mo, Ti, and Al. Current–voltage characteristics revealed that Schottky barrier heights determined using a thermionic emission (TE) model (ϕBTE) were ranged between 1.90 eV for Pt and 2.56 eV for Mo depending on the work function ( ϕm) of the Schottky metals. Despite their low ϕm, Ti and Al gave unusually small ϕBTE probably due to the interfacial reaction between metal and p-type GaN. We also found that Mo/p-GaN SBDs exhibited a clear rectifying property even at 800 K, and the thermionic emission diffusion (TED) model explained well their high-temperature I–V characteristics. Furthermore, the temperature variation of Schottky barrier heights determined using a TED model (ϕBTED) almost agrees with half of the temperature variation of the bandgap energy. These findings will be helpful for the application of p-type GaN Schottky interfaces to high-power and high-temperature electronics.