Novel Photon-Counting Energy-Resolving Ultra-Fast X-Ray Detector

We propose to explore extremely fast digital switching devices used in telecommunications for use as photon counting, energy resolving x-ray detectors. The HEMT (High Electron Mobility Transistor), used in ultra-fast switches and low noise amplifiers, offers a very low noise and high frequency operation (up to 600GHz has been achieved). For this study a novel HEMT-based photon-counting energy-resolving ultra-fast x-ray detector is proposed and studied via simulations. The hypothesis is that the x-ray interactions in the HEMT device will be detected by monitoring the degradation in a data bit transmission (gating time and counting for bit errors) across the transistor. By monitoring the bit error rate and time for error free vs. erroneous transmission, one can calibrate and estimate the x-ray flux and energy, respectively. The interactions of high energy photons are simulated using PENELOPE Monte-Carlo code system, and device simulations are performed with the SILVACO device simulation package. Deposited charge profiles within the device for x-ray photons and also the effects of photon absorption on the transient device current are simulated. The simulated absorption events trigger a disturbance in the transient drain current in the simulated device which can be used to detect individual photons in an energy resolving manner via digital or analog schemes.