The effect of doping the M-barrier in very long-wave type-II InAs∕GaSb heterodiodes

Abstract

A variation on the standard homodiode type-II superlattice with an M-barrier between the π-region and the n-region is shown to suppress the dark currents. By determining the optimal doping level of the M-superlattice, dark current densities of 4.95mA∕cm2 and quantum efficiencies in excess of 20% have been demonstrated at the moderate reverse bias of 50mV; allowing for near background-limted performance with a Johnson-noise detectivity of 3.11×1010cmHz∕W at 77K for 14.58μm cutoff wavelength for large area diodes without passivation. This is comparable to values for the state-of-the-art HgCdTe photodiodes.