Multicolor infrared detection realized with two distinct superlattices separated by a blocking barrier

A multicolor infrared photodetector was realized with two superlattices separated by a blocking barrier. The photoresponse is switchable between 7.5-12 and 6-8.5 mum by the bias polarity, and is also tunable by the bias magnitude in each wavelength regime. In addition, our detector exhibits advantages including little temperature dependence of the spectral response and the same order of responsivity in the two wavelength regimes. The measured peak responsivities in the two regimes are 117 mA/W at 9.8 mum under 1 V and 129 mA/V at 7.4 mum under -0.8 V, respectively. Also, the detectivities are comparable with the conventional multistack detector. The zero background peak detectivities are 2.3x10(10) cm Hz(0.5)/W at 50 K and 9.8 mum under 0.7 V, and 8.7x10(10) cm Hz(0.5)/W at 70 K and 7.4 mum under -0.7 V. (C) 2002 American Institute of Physics.