Drift mobilities in amorphous silicon
The author studied the nonlinear effects of the electric field on the drift mobilities of both electrons and holes in a series of undoped hydrogenated amorphous silicon (a-Si:H) and silicon-germanium alloy specimens. The author measured the transient photocurrents in pin diode structures as a function of electric field and temperature. Time-of-flight and charge collection measurements were conducted from which we concluded that the quantum efficiency for photo-carrier generation varied less than 10% for all specimens in this temperature and electric field range. In all cases transport was dispersive, but no evidence for field-dependence of the dispersion itself was found. The characteristic electric field for the onset of nonlinear electron transport increased with Ge concentration. In a-Si:H the author found a slight evidence for nonlinear transport of holes. The author presents a photocharge transient technique which allowed probing of the drift of electrons in several undoped a-Si:H specimens. The author found a unique feature of the transient photocharge associated with the thermal emission of the trapped electrons, strongly indicating that recombination occurs well after deep-trapping. The temperature dependence of the emission time revealed the mean energy of the trap distribution and the attempt-to-escape frequency associated with this trap. The author analyzed transient photocurrent and time-of-flight measurements in undoped a-Si:H for photocarrier motion both parallel and perpendicular to the thin-film growth axis. The author found a good agreement of the electron drift-mobility measurements and the electron mobility-lifetime product estimates for the two field directions for fifteen specimens. The data exclude an electron transport anisotropy in a-Si:H greater than a factor of two.
- Research Organization:
- Syracuse Univ., NY (United States)
- OSTI ID:
- 7156806
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Research on Defects and Transport in Amorphous-Silicon-Based Semiconductors, Annual Subcontract Report, 20 February 1992 - 19 February 1993
Electron and hole dynamics in amorphous silicon
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
GERMANIUM ALLOYS
ELECTRON DRIFT
ELECTRON MOBILITY
HOLE MOBILITY
SILICON
AMORPHOUS STATE
PHOTOCURRENTS
TRAPS
ALLOYS
CURRENTS
ELECTRIC CURRENTS
ELEMENTS
MOBILITY
PARTICLE MOBILITY
SEMIMETALS
665000* - Physics of Condensed Matter- (1992-)
360606 - Other Materials- Physical Properties- (1992-)