Solar-blind photodetectors and focal plane arrays based on AlGaN

Ryan P McClintock, Manijeh Razeghi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


III-Nitride material system (AlGaInN) possesses unique optical, electrical and structural properties such as a wide tunable direct bandgap, inherent fast carrier dynamics; good carrier transport properties, high breakdown fields; and high robustness and chemical stability. Recent technological advances in the wide bandgap AlGaN portion of this material system have led to a renewed interest in ultraviolet (UV) photodetectors. These detectors find use in numerous applications in the defense, commercial and scientific arenas such as covert space-To-space communications, early missile threat detection, chemical and biological threat detection and spectroscopy, flame detection and monitoring, UV environmental monitoring, and UV astronomy.1,2,3 Back illuminated detectors operating in the solar blind region are of special interest. Back illumination allows the detector to be hybridized to a silicon read-out integrated circuit, epi-side down, and still collect light through the back of the transparent sapphire substrate. This allows the realization of solar blind focal plane arrays (FPAs) for imaging applications. Solar-blind FPAs are especially important because of the near total absence of any background radiation in this region. In this talk, we will present our recent back-illuminated solar-blind photodetector, mini-Array, and FPA results. By systematically optimizing the design of the structure we have realized external quantum efficiencies (EQE) of in excess of 89% for pixel-sized detectors. Based on the absence of any anti-reflection coating, this corresponds to nearly 100% internal quantum efficiency. At the same time, the dark current remains below ∼2 × 10-9 A/cm2 even at 10 volts of reverse bias. The detector has a very sharp falloff starting at 275 with the UV-solar rejection of better than three orders of magnitude, and a visible rejection ratio is more than 6 orders of magnitude. This high performance photodetector design was then used as the basis of the realization of solar-blind FPA. We demonstrated a 320×256 FPA with a peak detection wavelength of 278nm. The operability of the FPA was better than 92%, and excellent corrected imaging was obtained.

Original languageEnglish (US)
Title of host publicationOptical Sensing, Imaging, and Photon Counting
Subtitle of host publicationNanostructured Devices and Applications
EditorsGail J. Brown, Manijeh Razeghi, Dorota S. Temple
ISBN (Electronic)9781628417210
StatePublished - Jan 1 2015
EventOptical Sensing, Imaging, and Photon Counting - San Diego, United States
Duration: Aug 11 2015Aug 13 2015

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherOptical Sensing, Imaging, and Photon Counting
Country/TerritoryUnited States
CitySan Diego


  • AlGaN
  • Focal Plane Array
  • Solar-Blind
  • Ultraviolet

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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