Perspective article on solar-blind UV photodetectors

A research group from the Indian Institute of Science has published a perspective article titled "The road ahead for ultrawide bandgap solar-blind UV photodetectors" in the Journal of Applied Physics.

Abstract:

This perspective seeks to understand and assess why ultrawide bandgap (UWBG) semiconductor-based deep-UV photodetectors have not yet found any noticeable presence in real-world applications despite riding on more than two decades of extensive materials and devices’ research. Keeping the discussion confined to photodetectors based on epitaxial AlGaN and Ga2O3, a broad assessment of the device performance in terms of its various parameters is done vis-à-vis the dependence on the material quality. We introduce a new comprehensive figure of merit (CFOM) to benchmark photodetectors by accounting for their three most critical performance parameters, i.e., gain, noise, and bandwidth. We infer from CFOM that purely from the point of view of device performance, AlGaN detectors do not have any serious shortcoming that is holding them back from entering the market. We try to identify the gaps that exist in the research landscape of AlGaN and Ga2O3 solar-blind photodetectors and also argue that merely improving the material/structural quality and device performance would not help in making this technology transition from the academic realm. Instead of providing a review, this Perspective asks the hard question on whether UWBG solar-blind detectors will ever find real-world applications in a noticeable way and whether these devices will be ever used in space-borne platforms for deep-space imaging, for instance.

Full text: https://aip.scitation.org/doi/full/10.1063/5.0082348

The chain of UWBG detector technology development: A general status.

State-of-art n-type (right axis) and p-type (left axis) conductivity values in epitaxial AlGaN as a function of the bandgap of the ternary alloy, as reported in the literature.

Scatter plot of the product of UV-to-visible rejection ratio and gain of various types of AlGaN solar-blind photodetectors, as published in the literature, benchmarked with a Hamamatsu commercial-grade solar-blind photomultiplier tube.

A possible blown-up schematic of deep-UV imaging assembly based on AlGaN photodetector, which can significantly cut down on weight, footprint, and complexities such as high voltage requirement.

A qualitative plot of the current status of solar-blind UV photodetectors vis-à-vis their approximate TRL levels for AlGaN, β-Ga2O3, α-Ga2O3, and ɛ-Ga2O3.