Theory of quantum well IR photodetectors with tunnelling electron injection

A simple analytical model of quantum-well infrared photodetectors (QWIPs) utilising intersubband electron transitions and tunnelling injection of electrons is developed. It is shown that the dark current and the responsivity as functions of the QWIP parameters, including the number of QWs, are expressed by means of solutions of a transcendent equation. This equation is valid for a wide range of parameters and conditions where QWIPs can exhibit effective operation. Explicit formulae for the dark current and the responsivity are obtained in some important cases. Nonlinear effects in the QWIP operation are considered and threshold values of bias voltage and intensity of infrared radiation are estimated