HOT-ELECTRON DISTRIBUTION IN MULTIPLE-QUANTUM-WELL INFRARED PHOTODETECTORS

The hot-electron distribution in the GaAs/AlxGa1-xAs multiple quantum well structure of 10-mum infrared photodetectors is measured with a bu ilt-in energy analyzer at different temperatures. The distribution wid th is found to depend strongly on T in the T almost-equal-to 40 to 90 K range. It increases with T, reaches a maximum at around 70 K, and th en decreases at higher T's. The experiment makes it possible to unambi guously identify thermally assisted tunneling as the dominant source o f the dark current at 77 K.