Ion-beam sputtered indium tin oxide for InP solar cells
The efficiency of indium tin oxide/indium phosphide (ITO/InP) solar cells depends on the rate of deposition of the ITO and the substrate temperature. In the case of rf sputter deposition, both of these parameters should be maintained as low as possible. However, it is still necessary to produce ITO window layers with as low a sheet resistance and high a transmittance as possible. This paper is concerned with the properties of such films fabricated by ion-beam sputtering under the above restrictive conditions. In particular, we have investigated the effects of varying the background partial pressure of oxygen, the film thickness, and the rate of deposition on the electro-optical properties of the films. (i) For very slow deposition rates (approx.0.3 A s/sup -1/) and low substrate temperatures (<40 /sup 0/C), resistivities of <7 x 10/sup -4/ ..cap omega.. cm have been obtained for films of thickness 250--1200 A. This was for a partial pressure of oxygen, <10/sup -6/ Torr; for a partial pressure of 4 x 10/sup -5/ Torr, the resistivity of the films increased to 2 x 10/sup -3/ ..cap omega.. cm. (ii) The refractive index increased from 1.95 to 2.00 over the same range of oxygen partial pressure. (iii) For very thin films, <200 A in thickness, the refractive index decreased to approx.1.75. (iv) Carrier mobility shows a transition from lattice scattering (..mu..approx.25 cm/sup 2/ V/sup -1/ s/sup -1/) to impurity scattering (25< ..mu..<15 cm/sup 2/ V/sup -1/ s/sup -1/) for a carrier density n> or approx. =3 x 10/sup 20/ cm/sup -3/. (v) The optical constants vary significantly across the solar spectrum with oxygen partial pressure and film thickness.
- Research Organization:
- Solar Energy Research Institute, Golden, Colorado 80401
- OSTI ID:
- 5663869
- Journal Information:
- J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 4:3; ISSN JVTAD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CARRIER MOBILITY
CHALCOGENIDES
DIMENSIONS
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELECTRICAL PROPERTIES
ELECTRO-OPTICAL EFFECTS
EQUIPMENT
FABRICATION
INDIUM COMPOUNDS
INDIUM OXIDES
INDIUM PHOSPHIDE SOLAR CELLS
MOBILITY
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
SOLAR CELLS
SOLAR EQUIPMENT
SPUTTERING
THERMODYNAMIC PROPERTIES
THICKNESS
TIN COMPOUNDS
TIN OXIDES
VAPOR PRESSURE