Calculation of the dark current in a quantum well infrared photodetector

Dark currents in a biased quantum well fabricated using Al0.27Ga0.73As/GaAs heterojunctions are calculated at two different temperatures including thermionic field emission currents arising from the electron scattering with phonons and plasmons. In the electron-phonon scattering process several modes due to heterojunctions such as the confined, half-space and interface longitudinal optic phonons are taken into account. It is found that the confined phonon scattering process results in maximum currents compared to those obtained in the half-space and interface scattering modes. However, the magnitude of the currents that resulted from the electron-plasmon scattering process is found to be higher than that found from the electron scattering with confined phonons. Comparison of the calculated dark currents with experiments shows that the thermionic emission currents due to phonon and plasmon assisted processes are essential to get better agreement with experiments than the previously employed bulk phonon scattering process.