Nanosecond BaF2 scintillators require photon-counting silicon detectors with high quantum efficiency at 220 nm—the fast component—while simultaneously suppressing the slow 330 nm background. BaF2 scintillators combine two of the greatest challenges facing photon-counting silicon detectors. First, deep ultraviolet silicon detectors are subject to instabilities and degradation caused by DUV photons. Second, solar-blind antireflection coatings are a sort of Holy Grail for deep ultraviolet silicon detectors, particularly for photon-counting detectors that cannot tolerate high levels of background from out-of-band radiation.

JPL’s Microdevices Laboratory has recently used nanometer-scale engineering of the Si-SiO2 interface to demonstrate major advances in solving both of these challenges. Using low-temperature molecular beam epitaxy, we have succeeded in growing a doping superlattice on back-illuminated silicon detectors, and demonstrating that these superlattice-passivated detectors are exceptionally stable against DUV-induced radiation damage. At the same time, we have grown antireflection coatings directly on silicon CCDs using atomic layer deposition, and demonstrated world record quantum deep ultraviolet efficiency. To solve the problems of high-speed BaF2 scintillators, we will use these atomic-scale growth technologies to develop solar-blind, superlattice-doped silicon avalanche photodiode detectors. In this talk, the structure, fabrication, and physics of visible-blind, superlattice doped silicon detectors will be presented.

Light refreshments will be served after the seminar.