Surface leakage current reduction in long wavelength infrared type-II InAs/GaSb superlattice photodiodes

Dielectric passivation of long wavelength infrared type-II InAs/GaSb superlattice photodetectors with different active region doping profiles has been studied. SiO(2) passivation was shown to be efficient as long as it was not put in direct contact with the highly doped superlattice. A hybrid graded doping profile combined with the shallow etch technique reduced the surface leakage current in SiO(2) passivated devices by up to two orders of magnitude compared to the usual design. As a result, at 77 K the SiO(2) passivated devices with 10.5 mu m cutoff wavelength exhibit an R(0)A of 120 Omega cm(2), R(max)A of 6000 Omega cm(2), and a dark current level of 3.5 x 10(-5) A cm(-2) at -50 mV bias. (C) 2011 American Institute of Physics. [doi:10.1063/1.3584853]