Unipolar Solid-State Photomultiplier Using a Wide Bandgap Semiconductor for DUV Detection

For understanding the physics beyond the standard model, deep UV (DUV) photodetectors can be employed for a myriad of applications. These include cryogenic liquid noble gas chambers to Cherenkov detector systems. Though photomultiplier tubes (PMTs) and silicon photomultipliers (SiPM) are used for these applications. The technology is limited in being bulky and high power (PMT) or having a moderate quantum efficiency and sensitivity to radiation (SiPM). An advanced DUV photodetector is proposed using beta-gallium oxide (ß-Ga2O3), which is an ideal candidate due to its wide band gap, tunable using aluminum up to Al2O3, as well as being inherently radiation tolerant. A n-Barrier-n (nBn) configuration utilizes wide bandgap insulators (e.g. MgO or Al2O3) as a barrier layer, providing a mechanism for the formation of depletion region, where avalanche gain is achievable yet keeping dark current low. Optimizing the design for operation beyond the breakdown voltage, a Geiger-photodiode can be obtained, leading to a ß-Ga2O3 solid-state photomultiplier. RMD, Inc. will assess feasibility of fabrication of DUV Ga2O3-based photodetectors using either an atomic layer deposition or sputter growth techniques. The Phase I effort will assess the quality of the growth of the material by evaluating test diodes formed from etching the epitaxy wafers. The project will conduct device simulations to demonstrate a viable design of a Geiger photodiode from the nBn configuration for the ultimate formation of a solid-state photomultiplier. The technology can be employed in liquid noble gas detector systems or for Cherenkov detectors. The Ga2O3 SSPMs has numerous applications, including but not limited to detection of biological agents, reagent-less PON diagnostics, micro-machining, non-line of sight communications, clandestine targeting and locating applications, synthetic biology identification, and compact atomic clocks.