Method and apparatus for determining minority carrier diffusion length in semiconductors
Method and apparatus are provided for determining the diffusion length of minority carriers in semiconductor material, particularly amorphous silicon, which has a significantly small minority carrier diffusion length using the constant magnitude surface-photovoltage (SPV) method. Steady or modulated illumination at several wavelengths provides the light excitation on the surface of the material to generate the SPV. A manually controlled or automatic servo system maintains a constant predetermined value of the SPB for each wavelength. A probe electrode immersed in an electrolyte solution containing redox couples (preferably quinhydrone) having an oxidation-reduction potential (E) in the order of +0.6 to -1.65 volts couples the SPV to a measurement system. The redox couple solution functions to create a liquid Schottky barrier at the surface of the material. The Schottky barrier is contacted by merely placing the probe in the solution. The redox solution is placed over and in contact with the material to be tested and light is passed through the solution to generate the SPV. To compensate for colored redox solutions a portion of the redox solution not over the material is also illuminated for determining the color compensated light intensity. Steady red light is also used as an optical bias to reduce deleterious space-charge effects that occur in amorphous silicon.
- Assignee:
- RCA Corporation
- Patent Number(s):
- US 4433288
- OSTI ID:
- 6893234
- Resource Relation:
- Patent File Date: Filed date 6 Jul 1981; Other Information: PAT-APPL-280918
- Country of Publication:
- United States
- Language:
- English
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Method and apparatus for determining minority carrier diffusion length in semiconductors
Method and apparatus for determining minority carrier diffusion length in semiconductors
Related Subjects
36 MATERIALS SCIENCE
DIFFUSION LENGTH
MEASURING METHODS
SEMICONDUCTOR MATERIALS
CHARGE CARRIERS
CONTROL SYSTEMS
DESIGN
ELECTRIC PROBES
ELECTRODES
ELECTROLYTES
EXCITATION
FIBER OPTICS
LIGHT SOURCES
MEASURING INSTRUMENTS
QUINHYDRONE
REDOX POTENTIAL
SCHOTTKY EFFECT
SERVOMECHANISMS
SILICON
SOLUTIONS
SPACE CHARGE
SURFACE POTENTIAL
WAVELENGTHS
AROMATICS
BENZOQUINONES
CONTROL EQUIPMENT
DIMENSIONS
DISPERSIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EQUIPMENT
LENGTH
MATERIALS
MIXTURES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
POTENTIALS
PROBES
QUINONES
RADIATION SOURCES
SEMIMETALS
420800* - Engineering- Electronic Circuits & Devices- (-1989)
360603 - Materials- Properties