Wavelength agile superlattice quantum dot infrared photodetector

A dual-band superlattice quantum dot infrared photodetector, providing bias-selectability of the response peaks, is demonstrated. The active region consists of two quantum dot superlattices separated by a graded barrier, enabling photocurrent generation only in one superlattice for a given bias polarity. Two response bands, one consisting of three peaks at 2.9, 3.2, and 4.9 mu m and the other consisting of three peaks at 4.4, 7.4, and 11 mu m, were observed up to 120 K for reverse and forward biases, respectively. The specific detectivity values at 80 K are 3.2 and 2.6x10(9) Jones for the 4.9 and 7.4 mu m peaks.