High-quality Schottky contacts to n - In Ga N alloys prepared for photovoltaic devices

Large-area Au ∕ Pt ∕ n - In 0.2 Ga 0.8 N Schottky contacts have been fabricated for photovoltaic devices. The current transport mechanisms of the Schottky contacts to n - In 0.2 Ga 0.8 N with different background carrier concentrations are investigated. The thermionic emission is a dominating current transport mechanism at the Pt ∕ n - In Ga N interface in a low background carrier concentration sample, while the defect-assisted tunneling current and trap-related recombination current play important roles in high background carrier concentration samples. The Schottky diode fabricated using the low background carrier concentration sample gives much better Schottky barrier characteristics and exhibits a three to four order of magnitude higher spectral responsivity and a larger rejection ratio in comparison with those fabricated using the high background carrier concentration samples.