Experimental Evaluation of the Average Energy for Impact Ionization by Holes in Al0.4Ga 0.6N Alloy

An experimental approach to evaluate the average energy required by holes for impact ionization in Al
_0.4
Ga
_0.6
N alloys is presented. A series of back-illuminated separate absorption and multiplication structures with different thickness of multiplication layer are employed. With the measured quantum efficiency of devices and a consideration of energy conservation in ionization process, the average energy for electron-hole pair production by energetic holes is obtained and it qualitatively agrees with the bond energy of Al
_0.4
Ga
_0.6
N, which is estimated from the Vegard's law.