Capacitance-voltage investigation of low residual carrier density in InAs/GaSb superlattice infrared detectors

Capacitance-voltage (CV) analysis was performed on homojunction InAs/GaSb superlattice photodiodes for the mid-infrared spectral range around 5μm. The CV investigation was carried out over a wide temperature range from 80 K up to 200 K, for two nominally identical samples from two different epitaxy systems. The characterizations were carried out with a refined measurement setup, considering the impedance range, the measured frequency range and the accessible temperature range. For the calculated residual carrier density in the nid-region of the diodes values in the low 1014 cm−3 and 1015 cm−3 ranges were found, respectively.