Effects of surface preparation on the properties of metal/CdTe junctions
The effects of surface preparation on the properties of single crystal CdTe junctions have been investigated through characterization of metal/CdTe junctions. Oriented surfaces include air-cleaved (110) surfaces, bromine-in-methanol etched (110) and (111) surfaces, and bromine-in-methanol etched surfaces subjected to a hydrogen heat treatment. Surface photovoltage measurements of the surfaces indicate larger band bending on the etched surfaces than on the cleaved and heat treated surfaces. X-ray photoelectron spectroscopy analysis verifies that excess Te remains after bromine-in-methanol etching and that cleaving leaves a stoichiometric surface. Hydrogen heat treatment of an etched CdTe surface restores a stoichiometric cleaved-like surface from that altered by the etching process. The barrier height for metal/CdTe junctions formed on cleaved surfaces depends on metal work function and reaches 0.99 V in an Al/CdTe junction and 0.87 V in a Cr/CdTe junction. Junctions formed with different metals on etched (110) surfaces result in barrier heights of 0.55--0.65 V with no dependence of the barrier height on the metal work function being observed, due to the presence of an etch-induced layer that partially governs the properties the surface. Heat treatment of an etched surface results in metal/CdTe junctions with characteristics similar to those of junctions formed on cleaved surfaces, and dependence of barrier height on metal work function is again observed, indicating the removal of an etch-induced layer by the heat treatment and the production of a junction similar to that on the cleaved surface.
- Research Organization:
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305
- OSTI ID:
- 5487184
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 54:10; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
CADMIUM COMPOUNDS
CADMIUM TELLURIDES
CHALCOGENIDES
CLEAVAGE
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELEMENTS
ETCHING
HEAT TREATMENTS
IONIZING RADIATIONS
JUNCTIONS
METALS
MICROSTRUCTURE
PHOTOELECTRON SPECTROSCOPY
POTENTIALS
RADIATIONS
SAMPLE PREPARATION
SEMICONDUCTOR JUNCTIONS
SPECTROSCOPY
SURFACE FINISHING
SURFACE POTENTIAL
SURFACE TREATMENTS
TELLURIDES
TELLURIUM COMPOUNDS
X RADIATION