Persistent photoconductance in doping-modulated and compensated a -Si:H
- The Department of Physics and The James Franck Institute, The University of Chicago, Chicago, Illinois (USA)
We present experimental results and numerical calculations in support of the following model to explain the origin of the persistent-photoconductivity effect (PPC) in {ital p}-{ital n} multilayers of hydrogenated amorphous silicon ({ital a}-Si:H): Small light exposures create Staebler-Wronski defects in the {ital p}-type regions of the multilayer, making these regions more intrinsic. This brings the equilibrium Fermi level of the multilayer closer to the conduction band in the depletion zones of the {ital n}-type regions, causing an increase in the conductance of the layered structure when the conductance is electron dominated. At large light exposures, the Staebler-Wronski defects created in the {ital n}-type regions pull the Fermi level away from the conduction band, decreasing the conductance of the film. Our experimental results show that, for a given light intensity, the creation rate and annealing kinetics of the PPC in multilayers are correlated with the creation rate and annealing kinetics of the light-induced conductance changes in unlayered {ital p}-type and {ital n}-type {ital a}-Si:H films having the same dopings as the {ital p}-type and {ital n}-type regions in the multilayer. The PPC follows a stretched-exponential time relaxation with the same parameters describing the decays of other metastable conditions in {ital a}-Si:H. Our computer calculations can reproduce the dark conductivity and magnitude of the PPC in a multilayer (doped at 100 ppm) as a function of sublayer thickness {ital d}, except for {ital d}{lt}20 nm.
- OSTI ID:
- 5170394
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 44:11; ISSN PRBMD; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
AMORPHOUS STATE
ANNEALING
CHEMICAL REACTIONS
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
HEAT TREATMENTS
HYDROGENATION
JUNCTIONS
MATERIALS
P-N JUNCTIONS
PHOTOCONDUCTIVITY
PHYSICAL PROPERTIES
SEMICONDUCTOR JUNCTIONS
SEMIMETALS
SILICON