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Deposition Method for Enhancing Laser Induced Thermoelectric Effects

IP.com Disclosure Number: IPCOM000082054D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Caswell, H: AUTHOR [+3]

Abstract

When thin films of molybdenum and tungsten, for example, are excited by a pulsed laser light at normal incidence to the film, transfer thermoelectric voltages are generated. Output voltages across a 50 ohm load of 10 millivolts have been observed for an incident laser pulse of approximately 1 KW. Wavelengths in the range of 0.46-1.06 mum and pulse widths of approximately 3-300 nanoseconds produce output voltages.

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Deposition Method for Enhancing Laser Induced Thermoelectric Effects

When thin films of molybdenum and tungsten, for example, are excited by a pulsed laser light at normal incidence to the film, transfer thermoelectric voltages are generated. Output voltages across a 50 ohm load of 10 millivolts have been observed for an incident laser pulse of approximately 1 KW. Wavelengths in the range of 0.46-1.06 mum and pulse widths of approximately 3-300 nanoseconds produce output voltages.

The output voltage from the film which may be considered a detector, in terms of polarity, may be reversed by reversing the direction of light incidence. Also, the direction in magnitude of the output may be controlled, by adjusting the position of the metallic film relative to a pair of contacts disposed in sliding relationship with the metallic film. An electrically insulating substrate is preferably used to cause a better temperature gradient normal to the plane of the film. In general, the response time of the films is dependent on the laser pulse width.

As indicated hereinabove, anisotropies are introduced during the deposition or growth process of the conductive film. It has been found that the magnitude of these voltages is affected by the angle that the evaporant beam makes with the substrate. A direct correlation has been found between the direction of the evaporant beam with respect to the substrate and the direction of the voltage maximum in the film. Also, a direct correlation is found to exist between the magnitude of this voltage and the angle between the normal to the substrate and...