HEMT-based photon-counting energy-resolving ultra-fast x-ray detector with improved sensitivity

We proposed 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. For this study a HEMT-based photon-counting energy-resolving ultra-fast x-ray detector with improved sensitivity is proposed and studied via simulations. The hypothesis is that the x-ray interactions within the structure 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. The aim of this study is to explore HEMT-based detector concept further and improve its sensitivity via incorporating a 500 um thick monolithically integrated absorber and study the characteristics of this new structure. We simulated cases for 10, 50 and 100 KeV photon energies, and the drain current pulse heights for the event detection of 10, 50 and 100 KeV photons were 4.18e-6A, 1.22e-5A, 1.98e-5A, respectively.