Radiometric and noise characteristics of InAs-rich T2SL MWIR pin photodiodes

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.

Influence of the p-type doping on the radiometric performances of MWIR InAs/GaSb superlattice photodiodes

“…To investigate an eventual non-optimal collection of the minority carriers suspected [16] in the InAs-rich SL structure, we decided to measure QE spectra of several InAs-rich samples with different active zone thicknesses (AZT). Fig.…”

“…Each QE spectrum was measured in two steps. First the relative photoresponse was measured using a FTIR spectrometer and then the absolute QE was calibrated using a SR200 blackbody [16].…”

“…Therefore to combine the long carrier lifetime of the InAs/InAsSb superlattice and the good QE of the T2SL, an InAs-rich T2SL was proposed [13]: this superlattice exhibits an InAs to GaSb thickness ratio close to R=2. Good performances in terms of dark current were already reported [13][14][15] but a recent study tends to prove a problem of minority carrier collection with this design [16] leading to non-optimal performances in terms of QE.…”

Radiometric characterization of type-II InAs/GaSb superlattice (t2sl) midwave infrared photodetectors and focal plane arrays

“…The quantum efficiency of photodiodes is in the range of 50%, which is a very satisfying value, even if not as high as the 80% QE published in MCT technology. T2SL also proved to have no excess noise and flat angular response as well [1]. We also pointed out that the long-term stability of T2SL technology is excellent, such that T2SL could get back into the race for high performance infrared detectors in the MWIR domain.…”

“…Quantum Efficiency (QE) measurements have been performed at 0V bias voltage on these 3 structures. First the relative photoresponse was measured using a FTIR spectrometer and then the absolute QE was calibrated using a SR200 blackbody [1]. The QE results were compared in Fig.…”