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Accession number;07A0043210
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| Title;THERMAL CONDUCTIVITY MEASUREMENTS OF BISMUTH TELLURIDE THIN FILMS BY USING THE 3 OMEGA METHOD |
| Author;
TAKIISHI MAKOTO
(Kyushu Inst. Technol., Graduate School, JPN)
TANAKA SABURO
(Kyushu Inst. Technol., Graduate School, JPN)
MIYAZAKI KOJI
(Kyushu Inst. Technol., JPN)
TSUKAMOTO HIROSHI
(Kyushu Inst. Technol., JPN)
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Journal Title;Thermophys Prop
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Journal Code:X0031A
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ISSN:0911-1743
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VOL.27th;NO.;PAGE.24-26(2006)
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| Figure&Table&Reference;FIG.5, REF.7 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;The thermal conductivity of a bismuth telluride (Bi2Te3) thin film is measured at room temperature by using the 3.OMEGA. method. The 3.OMEGA. method for thin films uses a single metal-line as both the heater and thermometer. An ac driving current at angular frequency .OMEGA. heat the surface of the sample at a frequency 2.OMEGA.. Since the resistance of a metal increases with temperature, temperature oscillations produce an oscillation of the electrical resistance at a frequency of 2.OMEGA.. Consequently, the voltage drop across the metal line has a small component at 3.OMEGA. that can be used to measure the temperature oscillations and the thermal response of the sample with Bi2Te3 thin film. The differential amplifiers are used to subtract the .OMEGA. component of the voltage for the measurement of the small 3.OMEGA. signal as shown in Fig. 1. The amplified 3.OMEGA. component and the attenuated reference voltage are acquired to a personal computer through a 16 bit DAC card. The Bi2Te3 is flash evaporated onto a glass substrate, the thickness of the Bi2Te3 film is 600nm. Silicon dioxide (SiO2) thin film is deposited on the Bi2Te3 thin film as an insulator, and the narrow Aluminum (Al) line and rectangular pads are made by evaporation through a shadow mask. The shadow mask of silicon (Si) with silicon nitride (Si3Ni4) thin film is prepared by standard micro-fabrication processes (Fig. 2). The length of a metal line is 2mm and the width is 18.4.MU.m (Fig. 3). The measured temperature oscillations .DELTA.T from 3.OMEGA. signal is shown in Fig. 4. The slope of .DELTA.T versus ln(.OMEGA.) yields the thermal conductivity of the glass substrate (0.97W/(m K)) as shown in Fig. 5. The thermal conductivity of Bi2Te3 thin film can be calculated from the thermal resistance between the metal line and the glass substrate. The measured thermal conductivity of a Bi2Te3 is 1.20W/(m K) and agrees with the reference data. (author abst.) |
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