Detection Wavelength of Strained In_xGa_1-x As/GaAs Very-Long-Wavelength Quantum Well Infrared Photodetectors

Detection wavelength is one of the key performance indices of infrared
photodetectors. We study the character of detection wavelength of the
strained In_xGa_1-x As/GaAs very-long-wavelength (>12μm) quantum well infrared photodetectors (VLW-QWIPs) characterized by the photoluminescence (PL) and photocurrent (PC) measurements. Based on the theoretical calculation and experimental data, we have built a practical model for the In_xGa_1-x As/GaAs strained VLW-QWIPs, from which the interband transitions, intersubband transition and peak detection wavelength can be determined. Afterwards, the dependences of detection wavelength and device operation mode on the In mole fraction and In_xGa _1-x As well width are presented, which will be helpful for device design and optimization.