Experimental and theoretical investigation of detection wavelength tuning in quantum well infrared-photodetectors by quantum well intermixing technique

Detection wavelength tuning of quantum well infrared photodetector (QWIP) has been carried out by using impurity free vacancy disordering (IFVD) technique with SiO/sub 2/ capping layer. The detection wavelength of QWIP was changed from 8.2/spl mu/m to 10/spl mu/m due to bandgap change by intermixing of constituent atoms in multiple quantum well (MQW) absorption region in Fig.1. The red-shift in detection wavelength can be explained by gap narrowing between confined state and continuum state in conduction band, which is a consequence of blue-shift in MQW bandgap after intermixing in Fig.2. The bandgap of the intermixed MQW structure was theoretically investigated. The Al-Ga inter-diffusion, which induces the red-shift of detection wavelength from 8.2/spl mu/m to 10/spl mu/m, was calculated to be 7/spl Aring/ at 850/spl deg/C.