Wide bandgap Geiger mode photodiodes in AlGaAs

Abstract

Emerging UV to blue light emitting scintillation materials promise improved radiation detection capabilities such as dual neutron-gamma detection and higher energy resolution. The use of traditional photomultiplier tubes (PMTs), with their associated high-voltage electronics often represents form factor and power-limiting component. The unique capabilities of a solid-state photomultiplier (SSPM) provides an alternative to PMTs. Though silicon based SSPMs (SiPMs) have been gaining wide attention in recent years, a major limiting factor is the dark current, especially for detectors that require sufficiently large detection area on a single chip. To scale up the detector area without drastic increase in dark current, we are developing new photodetector elements in Al 0.8 Ga 0.2 As. The wide-band-gap characteristic, combines with the maturity of GaAs material processing, makes Al 0.8 Ga 0.2 As an excellent material for developing large area SSPMs with lower dark current and high detection efficiency within the blue to UV region, which is important for state-of-the-art scintillation materials, such as LaBr3, CeBr3, and CLYC. This work presents the design, fabrication, and characterization results of Al 0.8 Ga 0.2 As Geiger mode photodiodes, as well as preliminary results of radiation hardness evaluation of these devices for harsh environment applications.