Spin split-off band-based high operating temperature IR detectors in 3-5 µm and beyond

Overcoming the stringent cooling requirement for the operation of most of the infrared (IR) detectors is one of the major challenges towards capturing their full potential. Split-off (SO) transitions based detector exhibit encouraging results and gives hope to provide a novel alternative to the conventional IR detectors operating with cryogenic aid. Recently, a GaAs/AlGaAs SO detector operating up to 330 K in the 3-5 μm spectral region was developed. This paper presents various design modifications including graded barrier (in place of flat barrier), and double barrier resonant structure (in place of a single barrier) to improve the performance of these detectors. The graded barrier improves the detector performance by reducing the space charge buildup due to the trapping of charge carriers at the emitter-barrier interface; additionally, the model implementation on GaAs/AlGaAs based detectors also suggests that a barrier offset of 20 meV approximately doubles the responsivity. The implementation of a double barrier resonant structure increases the escape of holes from the SO to the light/heavy hole (LH/HH) bands by bringing the two bands into resonance and increases the response by a factor of ~ 85. The results from our ongoing efforts to extend the concept of SO mechanism based IR detection towards longer wavelength are also presented. This should be possible by exploiting SO absorption in alternative material systems such as phosphides and nitrides. The successful utilization of SO mechanism can result in the high operating temperature detectors operating in mid-IR and terahertz (THz) region.