Short-wavelength infrared InAs/GaSb superlattice hole avalanche photodiode

We demonstrate two short-wavelength infrared avalanche photodiodes based on InAs/GaSb superlattice grown by metal-organic chemical vapor deposition.The difference between the two devices,namely,p+n-n+and p+nn-n+,is that the p+nn-n+device possesses an additional middle-doped layer to separate the multiplication region from the absorption region.By properly controlling the electric field distribution in the p+nn-n+device,an electric field of 906 kV/cm has been achieved,which is 2.6 times higher than that in the p+n-n+device.At a reverse bias of-0.1 V at 77 K,both devices show a 100%cut-off wavelength of 2.25μm.The p+n-n+and p+nn-n+show a dark current density of 1.5×10^-7 A/cm^2 and 1.8×10^-8 A/cm^2,and a peak responsivity about 0.35 A/W and 0.40 A/W at 1.5μm,respectively.A maximum multiplication gain of 55 is achieved in the p+nn-n+device while the value is only less than 2 in the p+n-n+device.Exponential nature of the gain characteristic as a function of reverse bias confirms a single carrier hole dominated impact ionization.