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.