Electron–hole pair creation energy in amorphous selenium: geminate versus columnar recombination

• Published in: Journal of materials science. Materials in electronics 2019-12, Vol.30 (24), p.21059-21063
• Main Authors: Kabir, M. Z., Arnab, Salman M., Hijazi, Nour
• Format: Article
• Language: English
• Subjects: Carrier recombination; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electric fields; Electron recombination; Electrons; Empirical analysis; Energy; Materials Science; Normal distribution; Optical and Electronic Materials; Photoconductors; Photoelectrons; Radiation; Room temperature; Selenium; Semiconductors; Sensors; X ray detectors; X ray irradiation; X-rays
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-02475-7

Amorphous selenium (a-Se) is one of the most successful photoconductors for direct-conversion X-ray detectors. However, the initial carrier recombination is believed to be responsible for high electron–hole pair (EHP) creation energy in a-Se. The simultaneously generated electron and its hole twin can recombine ( geminate recombination) or the non-geminate electrons and holes in the columnar track of the primary photoelectron can also recombine (columnar recombination). The question of which mechanism (geminate or columnar) dominates in X-ray irradiation has not been resolved. In this paper, we examine these two recombination mechanisms and analyze them by fitting with published experimental data. The analysis and results are consistent with the columnar recombination mechanism at X-ray irradiation. We also propose an empirical expression for the electric field and photon energy-dependent EHP creation energy in a-Se at room temperature.