Graduation Year

2005

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Shekhar Bhansali, Ph.D.

Committee Member

Larry Langebrake, P.E.

Committee Member

Kenneth Buckle, Ph.D.

Committee Member

Sang Chae Kim, Ph.D.

Keywords

Transition elements, Gold, Diffusion, Resistivity, Resistance

Abstract

A bulk silicon temperature sensor is fabricated in this work. The objective is to develop a low-cost high resolution temperature sensor. The target applications are a Conductivity-Temperature-Depth (CTD) sensor for oceanic applications and a magnetocaloric microcooler.

The properties of silicon are modified by thermal diffusion of gold. Gold is a fast diffuser in silicon and its diffusion contributes to the increase in resistivity of silicon. The addition of gold to n-type silicon creates a negative temperature coefficient device. The effect of the diffusing environment was investigated by diffusing in oxygen and nitrogen ambient at various temperatures. The influence of area of gold diffusion was also investigated. The effect of temperature on resistance was measured and was used to calibrate the sensor.

Although the sensors fabricated in an oxygen environment have an exponential type response, they can be used in the CTD application because of enhanced sensitivity in the 10˚C - 30˚C temperature range. Sensors fabricated in a nitrogen environment are found to have linear response with sensitivity ranging from 7Ω/˚C to 3000Ω/˚C and can be used for both applications. The fabricated sensors have a 0.1˚C resolution.

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