Large Area InGaN/GaN MQW p-i-n Avalanche Photodiode Cherenkov Radiation Detectors

C55-24a-270746For high energy physics experiments, the ring image Cherenkov (RICH) technique and the detection of internally reflected Cherenkov light (DIRC) are powerful tools. State of the art and future systems have to detect as few as a single Cherenkov photon in a high multiplicity environment with the best possible efficiency and with excellent time resolution. Photomultipliers (PMTs) and their variants are used but they suffer from strong sensitivity to magnetic fields and therefore force a complicated mechanical design. The transit time spread of standard PMTs is 250 ps or more which limits the achievable time resolution. Therefore, a strong need remains for a small size, compact, high rate, and magnetic field tolerant photo detector, such needs may be met by properly designed solid state devices. Due to magnetic field sensitivity of PMTs, a complex bulky design is used to avoid noise which limits the lifetime and range of applications. Thus, opportunities exist for magnetic field tolerant materials, especially for the semiconductors. While, Si based single photon counters are used, their response to UV light (the emission due to high energy particles is in the UV and deep UV region) is poor. Therefore, we propose the use of III-Nitride-based materials (thanks to their bandgap tunability from 206 nm to IR) single photon detector (SPD) developing p-i-n InGaN/GaN multiple quantum well avalanche photodiodes (APD) is highly feasible. The efficiency of III-Nitride based SPD-APD will be improved by suppressing the threading dislocations of structure by incorporating an AlGaN based superlattice. The dark current will also be suppressed by suppressing the threading dislocations, ultimately reducing the unwanted recombination sites. The overall effect of reducing dark current channels will lead to high single photon detection efficiency (SPD). In Phase II, our device will be waterproof packaged and will be used for Cherenkov light detection followed by image development demonstrating RICH. In Phase III, we will market such packaged devices. In Phase I, we will start from GaN growth on sapphire substrates and conduct the characterizations such as AFM, HRD, and Hall Effect measurements. After achieving high crystal quality, n-type GaN will be grown using Si as dopant followed by InGaN/GaN multiple quantum well structures optimized for absorption below 450 nm. Then a p-type GaN layer will be grown using Mg as a p-type dopant to form the p-i-n avalanche photodiode. The avalanche photodiode will be operated in linear mode to use as single photon detector. We will form an array of SPD-APDs that are ~25 × 25 µm2 over the area of a 100 mm substrate. The proof-of-concept device will be demonstrated at the end of Phase I. The single photon detection efficiency will be used as feedback to refine the design and device structure for Phase II proposal/work. The commercialization plan will be implemented at the end of Phase I which will be given in details in the Phase II proposal.