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/cm2, equivalent to a gain normalized dark current of ∼5 x 10‐6 A/cm2 is obtained (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High-Gain InAs Avalanche Photodiodes

“…13. Similar to the report in [4], for a given bias voltage the multiplication gain decreases significantly at 77 K, which is opposite to most III-V semiconductors. The gain difference between the structure in [4] and the graded structure here are much smaller at 77 K than at 300 K. This is consistent with the conclusion in Ref.…”

“…Similar to the report in [4], for a given bias voltage the multiplication gain decreases significantly at 77 K, which is opposite to most III-V semiconductors. The gain difference between the structure in [4] and the graded structure here are much smaller at 77 K than at 300 K. This is consistent with the conclusion in Ref. [7], where it was found that unlike at room temperature, at 77 K a thicker depletion region does not result in higher gain because the electron ionization coefficient has stronger dependence on electric field at 77 K. Therefore at 77 K, the gain of the graded structure reported here is only comparable to the gain reported in Ref.…”

“…[7], where it was found that unlike at room temperature, at 77 K a thicker depletion region does not result in higher gain because the electron ionization coefficient has stronger dependence on electric field at 77 K. Therefore at 77 K, the gain of the graded structure reported here is only comparable to the gain reported in Ref. [4] even though the graded structure has wider depletion region. To investigate the origin of smaller gain at 77 K, Monte Carlo simulations were performed.…”

“…The saturation of dark current below 100 K is due to background radiation. Unlike the work in [4], the size-dependent study of dark current in Fig. 8(b) indicates that the dark current of the graded structure InAs APDs is primarily bulk-dominated at all temperatures.…”

“…These results are also consistent with k~0. The measured gain versus bias voltage of the 6-μm i-region InAs APD in [4] and the graded structure reported here at 77 K are plotted in Fig. 13.…”