Beryllium compensation doping of InAs∕GaSb infrared superlattice photodiodes

Capacitance-voltage measurements in conjunction with dark current measurements on InAs∕GaSb long wavelength infrared superlattice photodiodes grown by molecular-beam epitaxy on GaSb substrates are reported. By varying the beryllium concentration in the InAs layer of the active region, the residually n-type superlattice is compensated to become slightly p type. By adjusting the doping, the dominant dark current mechanism can be varied from diffusion to Zener tunneling. Minimization of the dark current leads to an increase of the zero-bias differential resistance from less than 4to32Ωcm2 for a 100% cutoff of 12.05μm