Field-Controlled Photogeneration and Free-Carrier Transport in Amorphous Selenium Films
- 15 September 1968
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 173 (3), 899-907
- https://doi.org/10.1103/physrev.173.899
Abstract
We have studied the photogeneration and transport of free carriers in amorphous selenium films under varying conditions of thickness, wavelength of the exciting radiation, and applied electric field. We have found that the efficiency of photogeneration is strongly field controlled, varying by two or more powers of 10 with the field changes reported. Using a technique based on time resolving the transport of free carriers across the film, we have measured deep-hole trapping times of 10-45 μsec and deep-electron trapping times of 40-50 μsec at room temperature. In addition, we have found hole-drift mobilities of 0.13-0.16 /V sec and electron-drift mobilities of 6.0-8.3× /V sec at room temperature, in good agreement with previous workers. These measurements allow an independent determination of the hole and electron range of (1.3-6.3)× /V and (2.4-3.1)× /V, respectively. The hole range measured in this new way is 20-100 times larger than previous determinations based on an inappropriate Hecht-type analysis, which is only a measure of the product of the generation and transport efficiency and not of the transport alone. The voltage dependence of the total transported charge cannot be described by a simple range limitation. The thickness scaling laws and the independent measurement of the range require that the photogeneration efficiency must depend on the applied electric field. It is suggested that the photogeneration step involves the field-aided thermal dissociation of a tightly bound hole-electron pair. This is indicated by the electric-field and wavelength dependence of the apparent quantum efficiency.
Keywords
This publication has 19 references indexed in Scilit:
- Trapping Processes in Amorphous SeleniumPhysical Review B, 1967
- Electronic States in Vitreous SeleniumPhysical Review B, 1965
- High-field effects in photoconducting cadmium sulphideJournal of Physics and Chemistry of Solids, 1965
- Photoinduced Discharge Characteristics of Amorphous Selenium PlatesJournal of Applied Physics, 1963
- Electron and Hole Transport in CdS CrystalsProceedings of the Physical Society, 1963
- Drift Mobilities of Electrons and Holes and Space-Charge-Limited Currents in Amorphous Selenium FilmsPhysical Review B, 1962
- The Hole Mobility in SeleniumProceedings of the Physical Society, 1960
- Some Electrical Properties of Amorphous Selenium FilmsJournal of Applied Physics, 1960
- Transit Time Measurements of Charge Carriers in Amorphous Selenium FilmsProceedings of the Physical Society. Section B, 1957
- Zum Mechanismus des lichtelektrischen Prim rstromes in isolierenden KristallenThe European Physical Journal A, 1932