Drift mobilities in amorphous silicon

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7156806

Antoniadis, H

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606 -- Other Materials-- Physical Properties-- (1992-)
665000* -- Physics of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
AMORPHOUS STATE
CURRENTS
ELECTRIC CURRENTS
ELECTRON DRIFT
ELECTRON MOBILITY
ELEMENTS
GERMANIUM ALLOYS
HOLE MOBILITY
MOBILITY
PARTICLE MOBILITY
PHOTOCURRENTS
SEMIMETALS
SILICON
TRAPS