Capacitance-Voltage Characterization and Dark Current Analysis of InAs/GaSb Superlattice Mid-Wavelength Infrared Detectors

InAs/GaSb type-II superlattice infrared detectors for the mid-infrared wavelength region are investigated using the capacitance-voltage characterization technique. The frequency dependent impedance of a reverse biased pin-diode enables the determination of the capacitance and the electrically active residual charge carrier concentration in the undoped region. This charge carrier concentration is significant for the minority charge carrier lifetime and the extent of the depletion region and therefore an important parameter of the photon detectors. Capacitance voltage characterization is optimally suited for the used high quality material with carrier concentration in the low 10¹⁴ cm^-3 region. The carrier concentration is used as an input parameter for the dark current analysis to ensure best results in modeling the measured data in a six-component current model. The understanding of the dark current limitations is crucial for the improvement of the electrooptical performance of photon detectors.