Avalanche multiplication and impact ionization in amorphous selenium photoconductive target

• Published in: Japanese Journal of Applied Physics 2014-03, Vol.53 (3), p.31401-1-031401-4
• Main Authors: Park, Wug-Dong, Tanioka, Kenkichi
• Format: Article
• Language: English
• Subjects: Avalanches; Carriers; Electric fields; Ionization; Ionization coefficients; Multiplication; Photoconductors; Selenium; Voltage
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.53.031401

The avalanche multiplication factor and the hole ionization coefficient in the amorphous selenium (a-Se) high-gain avalanche rushing amorphous photoconductor (HARP) target depend on the electric field. The phenomenon of avalanche multiplication and impact ionization in the 0.4-µm-thick a-Se HARP target is investigated. The hot carrier energy in the 0.4-µm-thick a-Se HARP target increases linearly as the target voltage increases. The energy relaxation length of hot carriers in the a-Se photoconductor of the 0.4-µm-thick HARP target saturates as the electric field increases. The average energy Eav of a hot carrier and the energy relaxation length λE in the a-Se photoconductor of the 0.4-µm-thick HARP target at 1 × 108 V/m were 0.25 eV and 2.5 nm, respectively. In addition, the hole ionization coefficient β and the avalanche multiplication factor M are derived as a function of the electric field, the average energy of a hot carrier, and the impact ionization energy. The experimental hole ionization coefficient β and the avalanche multiplication factor M in the 0.4-µm-thick a-Se HARP target agree with the theoretical results.