Highly Reflective Low Resistance Pt/Ag/Ni/Au Based Ohmic Contacts on p-GaN
A metallization scheme of Pt/Ag/Ni/Au (0.6/120/20/40 nm) metal layers with high reflectance and good surface morphology has been developed for obtaining low resistance ohmic contact on p-GaN. These metal layers were deposited by electron beam evaporation system on p-GaN. The metal contacts were annealed in different ambient conditions (N2, air and N2 + O2). The as-deposited contacts exhibit nonlinear current-voltage behaviour with reflectivity of ~95% at 470 nm wavelength. The air annealed Pt/Ag/Ni/Au contacts at 500 °C exhibit linear current-voltage behaviour with low specific contact resistance of 2.4 × 10−2 Ω-cm2. The reflectivity of air annealed contact at 500 °C was decreased to ~88.4% at ~470 nm compared to as-deposited contacts (~95%).
Keywordsp-GaN Highly reflective ohmic contacts Rapid thermal annealing Surface morphology
This work was supported by council of scientific and industrial research (CSIR) under network programme (NWP-55).
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