Capacitance-voltage investigation of high-purity InAs∕GaSb superlattice photodiodes

The residual carrier backgrounds of binary type-II InAs∕GaSb superlattice photodiodes with cutoff wavelengths around 5μm have been studied in the temperature range between 20 and 200K. By applying a capacitance-voltage measurement technique, a residual background concentration below 1015cm−3 has been found. At temperatures below 100K carrier freeze-out is observed with a thermal activation energy of 4.5meV, leading to net carrier concentrations at 77K in the mid 1014cm−3.