Comparison of InGaAs and type-II Superlattice Based Extended SWIR Detectors

Abstract

In this work, the characteristics of metamorphic grown InGaAs based and InAs/GaSb/AlSb/GaSb Type-II superlattice based extended short wave infrared(eSWIR) detectors are reported. The InGaAs detector was a p-i-n photodiode(PD) with a planar structure, and the T2SL detector was an nBn barrier infrared diode with mesa structure. In case of InGaAs detector, the cutoff wavelength is 2.35 μm and average quantum efficiency(QE) in the 1.1-2.2 μm spectral range is 70.1 % under front-side illumination condition and 200 K operation. At 200K, the dark current density is 6.80×10-9 A/cm2 under -0.1 V bias and the expected peak specific detectivity is 2.33×1013 cm·Hz 1/2/W. In case of T2SL, the cutoff wavelength is 2.45 μm and average QE in the 1.1-2.2 μm spectral range is 51.3 % at 200 K. The dark current density at 200 K is 1.1×10-7 A/cm2 and the expected peak specific detectivity is 4.68×1012 cm·Hz 1/2/W at 200 K. The 1280×1024 infrared focal plane array(FPA) with the pixel size of 10 μm is fabricated and hybridized with readout integrated circuit. The InGaAs FPA show relatively low operability due to defect or cross hatch pattern of wafer while its specific detectivity is higher than T2SL.