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 μm and the other consisting of three peaks at 4.4, 7.4, and 11 μm, were observed up to 120 K for reverse and forward biases, respectively. The specific detectivity values at 80 K are 3.2 and 2.6×109 Jones for the 4.9 and 7.4 μm peaks.