Annealing and Measurement Temperature Dependence of W2B- and W2B5-Based Rectifying Contacts to p-GaN
Authors: Voss, L.F.; Stafford, L.; Thaler, G.T.; Abernathy, C.R.; Pearton, S.J.; Chen, J.-J.; Ren, F.
Source: Journal of Electronic Materials, Volume 36, Number 4, April 2007 , pp. 384-390(7)
Abstract:Schottky contact formation on p-GaN using W2B/Pt/Au and W2B5/Pt/Au 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 W2B- and W2B5-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.
Document Type: Research Article
Affiliations: Email: firstname.lastname@example.org
Publication date: April 1, 2007