Annealing and Measurement Temperature Dependence of W2B- and W2B5-Based Rectifying Contacts to p-GaN

Abstract

metallization schemes was investigated using x-ray photoelectron spectroscopy (XPS), current-voltage (I-V), and Auger electron spectroscopy measurements. The Schottky barrier height (SBH) determined from XPS is 2.71 eV and 2.87 eV for as-deposited W 2 B-and W 2 B 5 -based contacts, respectively. By comparison, fitting of the I-V curves using the thermionic field emission model gives unphysical SBHs > 4 eV due to the presence of an interfacial layer acting as an additional barrier to carrier transport. Upon annealing to~600-700°C, the diodes show slight deterioration in rectifying behavior due to the onset of metallurgical reactions with the GaN. The experimental dependence of the reverse leakage current on bias and measurement temperature is inconsistent with both thermionic emission and thermionic field emission models, suggesting that leakage must originate from other mechanisms such as surface leakage or generation in the depletion layer through deep-level defects.

Electronic transport and Schottky barrier heights of Pt/n-type GaN Schottky diodes in the extrinsic region

“…Sawada et al 12 suggested that these additional currents seem to modify the TE current and apparently lower the Schottky barrier height from J-V measurements. Stafford et al 32 and Voss et al 33 used a similar approach to analyze the I-V characteristics of boride-based contacts on p-type GaN.…”