Improved Energy Resolution in Amorphous Selenium X-ray Detectors via Unipolar Charge Sensing
IEEE Electron Device Letters, vol.47, no.8, pp.1635-1638, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 47 Issue: 8
- Publication Date: 2026
- Doi Number: 10.1109/led.2026.3707424
- Journal Name: IEEE Electron Device Letters
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Compendex, INSPEC, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Page Numbers: pp.1635-1638
- Keywords: Amorphous selenium, pulse height spectrum, rise-time, spectral imaging, unipolar charge sensing structure
- Middle East Technical University Affiliated: Yes
Abstract
This letter presents a unipolar charge-sensing amorphous selenium (a-Se) detector architecture addressing spectral limitations of conventional planar designs, where incomplete, depth-dependent electron collection leads to photopeak broadening and low-energy tailing. Detectors with 20 μm pixel pitch were fabricated and characterized using pulse-height spectroscopy. Transient measurements indicate that unipolar sensing effectively suppresses the influence of slow electron transport on the detector response, reducing rise time from 0.6–22.4 μs to 150 ± 11 ns. The proposed architecture achieves an energy resolution of 8.3 keV FWHM at 59.5 keV with suppressed spectral tailing, demonstrating a scalable pathway toward high-performance a-Se photon-counting detectors for applications such as spectral mammography.