Abstract

GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) have attracted much interest in the past several years. Highly uniform large area pixel arrays of 256 × 256 and 640 × 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 1.0µm of top and bottom Si-doped (5×10¹⁷/cm³) GaAs contact layers. In theoretical anatysis, the shape of quantorn 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 current-voltage (I-V) characteristics of the QWIP device. We have also found that the responsivity is asymmetrical under forward and reverse bias voltages. In this report, we will 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).

© 2000 IEEE