InGaAs photodetector with 1 fA dark current at 15µm pixel pitch

ASELSAN has made significant progress on developing its short-wave infrared (SWIR) technology, with a focus on improving dark current, quantum efficiency, and operability. In recent work, shunt current and generation-recombination current have been identified as the predominant dark current mechanisms. Shunt current can be suppressed by reducing the dangling bond count which requires optimizing the focal plane array passivation, and generation-recombination current can be reduced by improving the device design. Extensive work on process optimization employing various passivation schemes combined with theoretical layer design has lowered the SWIR focal plane array pixel dark current values down to < 1 nA/cm². Furthermore, achieving low dark current without sacrificing high quantum efficiency (exceeding 80%), by building on the previous process and post-process work, has enhanced the sensor's ability to capture faint signals. 640x512 format and 15 μm pitch SWIR focal plane arrays coupled with ASEL64015CG read-out circuits have consistently reached > 99.9% operability. After maturing the development work, ASELSAN launches its SWIR detector, LEOP-640/15-SW, pioneering the company's photodetector production. In this paper, the results of the theoretical and experimental R and D work on LEOP photodetector development and production at ASELSAN are presented.