Abstract
We present a full characterization of the radiometric performances of a type-II InAs/GaSb superlattice pin photodiode operating in the mid-wavelength infrared domain. We first focused our attention on quantum efficiency, responsivity and angular response measurements: quantum efficiency reaches 23% at λ = 2.1 µm for 1 µm thick structure. Noise under illumination measurements are also reported: noise is limited by the Schottky contribution for reverse bias voltage smaller than 1.2 V. The specific detectivity, estimated for 2π field-of-view and 333 K background temperature, was determined equal to 2.29 × 1010 Jones for -0,8 V bias voltage and 77 K operating temperature.
Highlights
AND PROBLEM STATEMENTType-II InAs/GaSb superlattice (T2SL) emerges as a good candidate to complete the main infrared technologies operating in the mid-wavelength infrared (MWIR) domain, because of its large effective mass and low Auger recombination rate [1]
We present a full characterization of the radiometric performances of a type-II InAs/GaSb superlattice pin photodiode operating in the mid-wavelength infrared domain
In the past six years many improvements have been reported such as a 70 % quantum efficiency (QE) for a T2SL focal plane array (FPA) [2](without antireflective coating, for 81 K operating temperature); a quantum efficiency of a T2SL photodiode was determined equal to 60 % for 150 K operating temperature [3]; a megapixel FPA was fabricated [4]
Summary
Type-II InAs/GaSb superlattice (T2SL) emerges as a good candidate to complete the main infrared technologies operating in the mid-wavelength infrared (MWIR) domain, because of its large effective mass and low Auger recombination rate [1]. An alternative pin photodiode structure using SL period with thicker InAs layer than GaSb layer (”InAs-rich” structure) was proposed to reduce the intrinsic carrier concentration (ni) [9] as compared with a symmetric design (same GaSb and InAs thickness) showing the same cut-off wavelength, and to reduce significantly the dark current. This promising InAs-rich structure, as confirmed by dark measurements [9, 10], requires a complete and rigorous radiometric characterization to assess the actual performances of this structure and to identify the limiting factors, if any.
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