Avalanche Multiplication in Schottky-type AlGaN Photodiode with High Al-composition

Shottky-type Al
_0.6
Ga
_0.4
N solar-blind avalanche photodiodes have been fabricated and characterized under front and back illuminated conditions. The photodiodes exhibited dark currents below 1pA in the measuring range. Photocurrent under front illumination was lower than photocurrent under back illumination in the reverse-bias region below 35 V, but then exceeded the latter as the reverse bias became larger. Impact ionization coefficient for electrons is larger than that for holes as derived from the gain-voltage curves under the front and back illuminations.