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. An unmodulated illumination 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 SPV. A vibrating Kelvin method-type probe electrode couples the SPV to a measurement system. The operating optical wavelength of an adjustable monochromator to compensate for the wavelength dependent sensitivity of a photodetector is selected to measure the illumination intensity (photon flux) on the silicon. Measurements of the relative photon flux for a plurality of wavelengths are plotted against the reciprocal of the optical absorption coefficient of the material. A linear plot of the data points is extrapolated to zero intensity. The negative intercept value on the reciprocal optical coefficient axis of the extrapolated linear plot is the diffusion length of the minority carriers. 5 figs.
- Assignee:
- RCA Corp., New York, NY (United States)
- Patent Number(s):
- US 4393348; A
- Application Number:
- PPN: US 6-228575
- OSTI ID:
- 7256241
- Resource Relation:
- Patent File Date: 26 Jan 1981
- 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