Broadening of optical transitions in polycrystalline CdS and CdTe thin films

Journal Article · Mon Nov 01 04:00:00 EDT 2010 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.3511744· OSTI ID:21464541

Jian, Li; Jie, Chen; Collins, R W ^[1]

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1. Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

The dielectric functions {epsilon} of polycrystalline CdS and CdTe thin films sputter deposited onto Si wafers were measured from 0.75 to 6.5 eV by in situ spectroscopic ellipsometry. Differences in {epsilon} due to processing variations are well understood using an excited carrier scattering model. For each sample, a carrier mean free path {lambda} is defined that is found to be inversely proportional to the broadening of each of the band structure critical points (CPs) deduced from {epsilon}. The rate at which broadening occurs with {lambda}{sup -1} is different for each CP, enabling a carrier group speed {upsilon}{sub g} to be identified for the CP. With the database for {upsilon}{sub g}, {epsilon} can be analyzed to evaluate the quality of materials used in CdS/CdTe photovoltaic heterojunctions.

• OSTI ID: 21464541
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 18 Vol. 97; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CADMIUM COMPOUNDS
CADMIUM SULFIDES
CADMIUM TELLURIDES
CHALCOGENIDES
CHARGE CARRIERS
CRYSTALS
DEPOSITION
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELEMENTS
ELLIPSOMETRY
ENERGY RANGE
EV RANGE
FILMS
HETEROJUNCTIONS
INORGANIC PHOSPHORS
LINE BROADENING
MATERIALS
MEAN FREE PATH
MEASURING METHODS
PERMITTIVITY
PHOSPHORS
PHOTOELECTRIC EFFECT
PHOTOVOLTAIC EFFECT
PHYSICAL PROPERTIES
POLYCRYSTALS
SEMICONDUCTOR JUNCTIONS
SEMICONDUCTOR MATERIALS
SEMIMETALS
SILICON
SPUTTERING
SULFIDES
SULFUR COMPOUNDS
TELLURIDES
TELLURIUM COMPOUNDS
THIN FILMS