The influence of interface roughness on the normal incident absorption of quantum-well infrared photodetectors

Thirty-period GaAs/AlGaAs quantum-well infrared photodetector (QWIP) samples with the same device structure prepared by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) are investigated in this paper. Temperature-insensitive responsivities observed for the devices are attributed to the unchanged photocurrent gain within the temperature range 10–77 K. Higher absorption for transverse electric mode infrared incident light observed for MBE-prepared QWIP is attributed to an increased interface light scattering resulted from MBE-prepared less smooth interfaces. In this case, higher normal incident absorption for the QWIP device prepared by MBE would be observed. Similar phenomenon observed for the MOCVD-prepared QWIP grown on 2° off (100) GaAs substrate is consistent with the argument.