Low noise high responsivity InAs electron avalanche photodiodes for infrared sensing

Abstract

Dark current measurements on SU-8 passivated InAs avalanche photodiodes (APDs) were carried out at temperatures ranging from 77 to 290 K. Extraction of the bulk and surface components suggested that the InAs APDs exhibit diffusion dominated bulk current and generation-recombination surface current. The activation energies obtained were 0.36 eV and 0.18 eV for bulk and surface components respectively. The responsivities of the InAs APDs were measured for wavelengths between 1.3 to 2 μm and the quantum efficiency was calculated to be ~50% across the measured wavelengths. The detectivity of the InAs diode was calculated based on the measured dark current density and responsivity. It was shown that the InAs APD has comparable detectivity with a commercial Judson InAs photodiode at temperatures of 200 to 290 K but has approximately 10 times higher detectivity than a commercial Hamamatsu InAs photodiode at 77 K. The potential of InAs APDs for infrared sensing is shown yielding high responsivity values and low dark current densities at 77 K. An avalanche multiplication factor of 22 with minimal excess noise factor at a dark current density of ~10 -4 A/cm 2, equivalent to a gain normalized dark current of ~5 x 10 -6 A/cm 2 is obtained. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.