Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Patent
1987-12-21
1989-08-22
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
324158D, 324 74, G01R 3126, G01R 3100
Patent
active
048599395
ABSTRACT:
A device for non-destructive surface photovoltage testing of silicon-on-sapphire (SOS) wafers employs the electrically equivalent of an inserted capacitance in series in a measuring circuit. A pair of thin irridescent coated (TIC) glasses, are positioned on each side of an SOS wafer with an electrical lead attached to each of the conductive coating of tin oxide and indium tin oxide of the TIC glasses. The glass surface (the non-conductive side) of each TIC glass is positioned adjacent to the sapphire layer and silicon layer respectively. An incident light illuminates the sapphire layer and subsequently illuminates the silicon-sapphire interface with a predetermined wave length of light wherein the silicon absorbs all of the light within about 100A of the silicon-sapphire interface. Thus, the incident light is transmitted through the conductive layer of the first TIC glass which is in electrical contact with a detection circuit. The second TIC glass conductive layer is in electrical contact with a calibration signal input which completes the measuring circuit. The measuring circuit with the electrical equivalent of a capacitor in series is able to detect the altered signal resulting from surface photovoltage (SPV) charge due to absorbed incident light which is a measure of the sapphire-silicon interface condition to permit a non-destructive SPV testing of SOS wafers, greatly speeding the pre-selection process of SOS wafers.
REFERENCES:
patent: 4494069 (1985-01-01), Lin
patent: 4563642 (1986-01-01), Munakata et al.
patent: 4642565 (1987-02-01), Jastrzebski et al.
Richard Williams, "Surface Photovoltage Measurements on Cadmium Sulfide", urnal Physical Chemical Solids, 23, 1057 (1962).
J. Lagowski, "Electronic Characterization of Heteroepitaxial Silicon-on-Sapphire by Surface Photovoltage Spectroscopy", J. Electrochem, Soc: Solid-State Science and Technology, 128, 2665 (1981).
Bozowski Stanley
Gittleman Jonathan I.
Burns William J.
Bush Freddie M.
Eisenzopf Reinhard J.
The United States of America as represented by the Secretary of
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