Effect of external electric field on photo-responsivity of CdS/ZnSe multiple quantum well photodetector

Abstract We show the enhancement of photo-responsivity through applied external electric field F of CdS/ZnSe multiple quantum well (MQW) photo-detector for the detection of mid infrared wavelengths. The subband energy levels En are calculated using the Schrodinger equation via finite difference method by incorporating exchange-correlation potential and Hartree potential caused by doping in the well layer. We note that by increasing F, En and the corresponding optical transition energies decreases. It is observed that dipole matrix element M21 reduces for higher F and we obtain approximately 38 % lower value of M21 at F = 40 kV/cm. Moreover, absorption coefficient decreases with F due to the strong dependence on M21. We obtain current density of 0.03 A/cm2 and responsivity of 0.012 A/W at wavelength λ = 2.73 μm for M (number of wells) = 20, well width Lw = 2 nm at F = 20 kV/cm. We show that the responsivity is enhanced by increasing M, Lw as well as doping concentration ND in the well. We also achieved higher photo-responsivity in CdS/ZnSe MQW using our proposed model as compared to the earlier reported results for GaAs/AlGaAs QWIP.