Noise characteristics of InAs/GaSb superlattice infrared photodiodes



A sophisticated noise measurement setup employing a switching unit to measure statistically relevant numbers of InAs/GaSb superlattice photodiodes has been developed. The noise current resolution limit of 20 fA Hz-1/2 enables the characterization of focal plane array-sized InAs/GaSb superlattice homojunction photodiodes for the long-wavelength infrared at 77 K. To resolve midwavelength infrared photodiodes a junction area of about (400 µm)2 is required. Without switching unit and by using a dedicated low noise amplifier, noise currents down to 2 fA Hz-1/2 can be achieved, allowing the noise characterization of mid-wavelength photodiodes with smaller junction areas. With this setup long-wavelength and mid-wavelength InAs/GaSb superlattice photodiodes, with generation-recombination limited dark current behavior, are investigated at 77 K. The measured diode noise follows the theoretically predicted shot noise level within the white noise part of the spectra. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)