Tunable NIR quantum well infrared photodetector using interband transitions

This paper presents the design and characterization of a near infrared (NIR) tunable quantum well infrared photodetector (QWIP). The detection was achieved using interband electron transitions between quantized energy levels for holes (light and heavy) in the valence band and quantized energy levels for electrons in the conduction band. The quantum wells are made asymmetric (step wells) to allow transitions between energy levels with different parity quantum numbers. The structure is modeled by solving self-consistently the Schrodinger and Poisson equations with the help of the shooting method. The photocurrent of the fabricated GaAs/InGaAs photodetector is measured at the temperature of 10 K and the observed response lies between 825 and 940 nm. When the bias is 0.5 V, a narrow response centered in 840 nm is achieved. Applying 4.5 V the peak response moves to 930 nm. The results demonstrate the possibility of tunable detection in the NIR band with great versatility.