Drift Mobilities of Electrons and Holes and Space-Charge-Limited Currents in Amorphous Selenium Films.
Abstract
The results of drift mobility and space-chargelimited crrent meaurements made on 20-micronthick films of amorphous Se were interpreted using the band model of a semiconducting solid with impurity or imperfection levels in the forbidden energy region between the conduction and valence bands. Drift mobilities were measured in the 220 to 300 K temperature range by determining the time of transit across the films of carriers which were photoinjected at one surface by 10 to the -8th power sec light pulses. The drift mobilities at 300 K were 0.165 sq cm/v sec for holes and 7.8 x 0.001 sq cm/v sec for electrons. The temperature dependence of hole mobility was exp(-0.14 ev/kT), and that of electrons was exp(-0.285 ev/kT). About 10 to the 19th power/cc electron traps were present in a 0.285-ev region just below the conduction band edge; about 10 to the 21st power/cc hole traps occupied a 0.14-ev portion of the gap immediately above the valence band edge. Au and Te electrodes were used to inject holes into amorphous Se, producing space-charge-limited currents at high fields. Electrical conductivities of 10 to the -14th to 10 to the -16th power/ohm/cm were obtained at low fields. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1961
- Accession Number
- AD0267838
Entities
People
- J.l. Hartke
Organizations
- University of Illinois Urbana–Champaign