Investigation of surface leakage reduction for small pitch shortwave infrared photodetectors

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2 Scopus citations

Abstract

Different passivation techniques are investigated for reducing leakage current in small pixel (down to 9 μm) heterostructure photodetectors designed for the short-wavelength infrared range. Process evaluation test chips were fabricated using the same process as for focal plane arrays. Arrays of small photodetectors were electrically characterized under dark conditions from 150 K to room temperature. In order to evaluate the leakage current, we studied the relation between the inverse of dynamic resistance at -20 mV and zero bias and perimeter over area P/A ratio as the pixel size is scaled down. At 150 K, leakage current arising from the perimeter dominates while bulk leakage dominates at room temperature. We find that in shortwave devices directly underfilling hybridized devices with a thermoset epoxy resin without first doing any additional passivation/protection after etching gives the lowest leakage with a surface resistance of 4.2 ×109 and 8.9 ×103 Ω cm-1 at 150 and 300 K, for -20 mV of bias voltage, respectively.

Original languageEnglish (US)
Article number06LT01
JournalSemiconductor Science and Technology
Volume34
Issue number6
DOIs
StatePublished - May 22 2019

Keywords

  • passivation
  • short wave infrared photodetector
  • small pixel size focal plane array
  • surface leakage current

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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