Demonstration of midinfrared type-II InAs/GaSb superlattice photodiodes grown on GaAs substrate

Abstract

We report the growth and characterization of type-II InAs/GaSb superlattice photodiodes grown on a GaAs substrate. Through a low nucleation temperature and a reduced growth rate, a smooth GaSb surface was obtained on the GaAs substrate with clear atomic steps and low roughness morphology. On the top of the GaSb buffer, a p+-i-n+ type-II InAs/GaSb superlattice photodiode was grown with a designed cutoff wavelength of 4 μm. The detector exhibited a differential resistance at zero bias (R0A) in excess of 1600 Ω cm2 and a quantum efficiency of 36.4% at 77 K, providing a specific detectivity of 6×1011 cmHz/W and a background limited operating temperature of 100 K with a 300 K background. Uncooled detectors showed similar performance to those grown on GaSb substrates with a carrier lifetime of 110 ns and a detectivity of 6×108 cmHz/W.