Magnetic field tunable terahertz quantum well infrared\ud photodetector
A theoretical model and a design of a magnetic field tunable CdMnTe/CdMgTe terahertz quantum\ud well infrared photodetector are presented. The energy levels and the corresponding wavefunctions\ud were computed from the envelope function Schr¨odinger equation using the effective mass\ud approximation and accounting for Landau quantization and the giant Zeeman effect induced by\ud magnetic confinement. The electron dynamics were modeled within the self-consistent coupled rate\ud equations approach, with all relevant electron-longitudinal optical phonon and electron-longitudinal\ud acoustic phonon scattering included. A perpendicular magnetic field varying between 0 T and 5 T,\ud at a temperature of 1.5 K, was found to enable a large shift of the detection energy, yielding a\ud tuning range between 24.1 meV and 34.3 meV, equivalent to 51.4 μm to 36.1 μm wavelengths. For\ud magnetic fields between 1 T and 5 T, when the electron population of the QWIP is spin-polarized,\ud a reasonably low dark current of ≤1.4×10–² A/cm² and a large responsivity of 0.36−0.64 A/W\ud are predicted.