Asymmetry is I-V characteristic and responsivity of GaAs/AlGaAs quantum well infrared photodetector

Summary form only given. GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) have attracted much interest in the past few years. Highly uniform large area pixel arrays of 256/spl times/256 and 640/spl times/480 and possessing excellent imaging performance have been achieved. The quantum well structure of the QWIP is designed in a symmetrical configuration with the infrared QW absorption layer sandwiched between 1.0 /spl mu/m of top and bottom Si-doped (5/spl times/10/sup 17/ /cm/sup 3/) GaAs contact layers. In theoretical analysis, the shape of the quantum well is normally assumed to be rectangular as well as symmetrical with atomically smooth interfaces. However, obvious asymmetry between positive and negative current is commonly observed from the measurement results of the current-voltage (I-V) characteristics of the QWIP device. We have also found that the responsivity is asymmetrical under forward and reverse bias voltages. We demonstrate that both of these factors contribute to the I-V current asymmetry of QWIPs by comparing samples grown by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD).