Low-cost, high-efficiency and ultrafast, broadband VUV-IR photon-counting hybrid photodetectors

Reliable, high-sensitivity, and high-efficiency photon-counting detectors, which can replace photomultiplier tubes (PMTs) in high energy physics and nuclear physics experiments, are of great interest to DOE. Other fields that could greatly benefit from these detectors include Cherenkov telescopes in astrophysics, positron emission tomography (PET) in medical imaging, space and planetary explorations, and other scientific, industrial and military applications. For many of these applications, the combination of a photocathode and a micro-channel plate (MCP) has been considered as a less bulky and more robust alternative to PMTs. However, for large-area coverage such as massive liquid-base particle detectors, or high-volume consumer applications, such as medical imaging, the high cost of these detectors limits their application. A major contributor to the cost of these detectors are the stringent production requirements, including the need for the assembly process to be done in ultrahigh vacuum. This project is directed toward the development of a hybrid photodetector consisting of a high-efficiency III-nitride based reflection-mode photocathode and a low-gain avalanche diode (LGAD) in an electron bombardment arrangement, which can be conveniently assembled under atmospheric pressures, before being sealed in a vacuum enclosure. The fabrication of the proposed Photoelectron-Bombardment- Avalanche-Diode (PEBAD) device will be compatible with economical and highly scalable batch production processes, similar to the ones used for commercial PMT production. Other advantages of the proposed PEBAD include a great flexibility in designing the photo-response spectrum including a very broadband operation, from deep ultraviolet (UV) to infrared (IR), or a bandpass photo-response without the use of inefficient and costly optical filters. Detection of light in the UV and deep UV range has a wide range of commercial, scientific and military applications, particularly in those areas where the shorter wavelength component of light needs to be analyzed in the presence of large visible and/or IR backgrounds. Gallium nitride (GaN) and its alloys with indium and aluminum are the most promising semiconductors for development of high-performance photodetectors. Wide-bandgap GaN-based devices are also extremely robust, and are suitable for operation in high temperatures and high radiation environments, which are required for some of the future DOE projects. The proposed low-cost and high-performance PEBAD device will enables a wide range of commercial applications.