Multicolor voltage tunable quantum-well infrared photodetector

Summary form only given. The authors present a novel concept of a multicolor QWIP (quantum-well infrared photodetector) by stacking the usual one-color QWIPs separated by thin (≈100 nm in the present test structure) conducting layers. They rely on the highly nonlinear and exponential nature of the device dark current-voltage characteristics. This implies that an applied voltage across the entire multistack would be distributed among the one-color QWIPs according to their values of DC resistances. Thus, when the applied voltage is increased from zero, most of the voltage will be dropped across the one-color QWIP with the highest resistance. As the voltage is further increased, an increasing fraction of the voltage will be dropped across the next highest resistance one-color QWIP, and so on. Since the detector responsivity of a one-color QWIP gradually turns on with applied voltage, one therefore can achieve a multicolor QWIP with spectral response peaks that turn on sequentially with an applied voltage. To demonstrate this concept, a three-color version of the multicolor QWIP has been fabricated