A GaAs/AlGaAs LED with SI-GaAs Substrate for X-ray Detection and Imaging: A Down-Conversion Method

GaAs-based light-emitting diodes (LEDs) are commonly employed in a variety of applications, including medical imaging, biosensing, optical communications, and night vision. In this paper, we present an alternative application of a GaAs-based LED with a semi-insulating GaAs (SI-GaAs) substrate for X-ray detection and imaging. The mechanism relies on the semiconductor frequency down-conversion process, where the SI-GaAs substrate acts as a photodetector (PD). Upon X-ray irradiation, the photocurrent generated by the SI-GaAs substrate drives the LED to emit NIR photons, which can be detected by a low-cost CCD. As a proof of concept, we have demonstrated X-ray detection and presented preliminary imaging results, providing another example of the applicability of the PD-LED design for optical frequency conversion. This down-conversion method of imaging eliminates the need for connecting readout circuits, therefore lowering the production cost and simplifying the manufacturing process. This PD-LED architecture leverages mature materials and fabrication processes and offers an alternative approach to X-ray detection and imaging. It has the potential to achieve devices with higher absorption, improved image resolution, and enhanced material stability.