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

Abstract

The residual carrier backgrounds of binary type-II $\mathrm{InAs}∕\mathrm{GaSb}$ superlattice photodiodes with cutoff wavelengths around $5\mathrm{\mu }\mathrm{m}$ have been studied in the temperature range between 20 and $200\mathrm{K}$ . By applying a capacitance-voltage measurement technique, a residual background concentration below ${10}^{15}{\mathrm{cm}}^{-3}$ has been found. At temperatures below $100\mathrm{K}$ carrier freeze-out is observed with a thermal activation energy of $4.5\mathrm{meV}$ , leading to net carrier concentrations at $77\mathrm{K}$ in the mid ${10}^{14}{\mathrm{cm}}^{-3}$ .