High quality photovoltaic semiconductor material and laser ablation method of fabrication same
A method is described of forming hydrogenated amorphous germanium alloy material, said material characterized by (a) the substantial absence of germanium hydrides, other than the monohydride, (b) a mobility-lifetime product for nonequilibrium charge carriers therein of about 10 [sup [minus]8] cm[sup 2]/V, and (c) a density of defect states in the band gap of the host matrix thereof of less than about 1 x 10[sup 17]/cm[sup 3]; said method comprising the steps of: providing a deposition chamber; providing a substrate in said deposition chamber; positioning at least one target of germanium containing material adjacent said substrate; providing a laser; evacuating said deposition chamber to a sub-atmospheric pressure; introducing into said evacuated deposition chamber a background gas including a partial pressure of at least hydrogen; and depositing, by laser ablation, germanium from said target and hydrogen from said partial pressure onto said substrate; thereby forming on said substrate a layer of hydrogenated germanium alloy material having an amorphous microstructure, said material characterized by the substantial absence of incorporated germanium hydrides, other than the monohydride, a mobility-lifetime product for nonequilibrium charge carriers therein of about 10[sup [minus]8] cm[sup 2]/V, and a density of defect states in the band gap of the host matrix thereof of less than about 1 x 10[sup 17]/cm[sup 3].
- Assignee:
- Energy Conversion Devices, Inc., Troy, MI (United States)
- Patent Number(s):
- US 5231047; A
- Application Number:
- PPN: US 7-811159
- OSTI ID:
- 6319366
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
ABLATION
AMORPHOUS STATE
CHARGE CARRIERS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEPOSITION
DIRECT ENERGY CONVERTERS
ELEMENTS
FABRICATION
GERMANIUM
GERMANIUM COMPOUNDS
GERMANIUM HYDRIDES
HYDRIDES
HYDROGEN COMPOUNDS
LASERS
MATERIALS
METALS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SEMICONDUCTOR MATERIALS
SUBSTRATES