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On-Chip Sensing of Thermoelectric Thin Film's Merit.

Xiao Z, Zhu X - Sensors (Basel) (2015)

Bottom Line: Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts.The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques.The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Alabama A&M University, Normal, AL 35762, USA. zhigang.xiao@aamu.edu.

ABSTRACT
Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques. Specifically, e-beam evaporation was used to grow the thermoelectric thin film of Sb2Te3 (100 nm thick). The Seebeck coefficient and the merit of the Sb2Te3 thin film were measured or determined. The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication.

No MeSH data available.


Related in: MedlinePlus

(a) SEM image of an enlarged view on a diode temperature sensor; (b) SEM image of a fabricated TE device for measurement of the in-plane Seebeck coefficient of Sb2Te3 thin film, where two diode temperature sensors were fabricated under the two ends of the Sb2Te3 film and separated by an insulation layer of SiO2.
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sensors-15-17232-f002: (a) SEM image of an enlarged view on a diode temperature sensor; (b) SEM image of a fabricated TE device for measurement of the in-plane Seebeck coefficient of Sb2Te3 thin film, where two diode temperature sensors were fabricated under the two ends of the Sb2Te3 film and separated by an insulation layer of SiO2.

Mentions: Managing heat flux has been one of the most important technical challenges that the current integrated circuit (IC) or MEMS industry is facing, because the rising temperature limits the miniaturization of IC or MEMS devices and decreases their lifetime [1]. Solid-state thermoelectric (TE) cooling techniques are of great interest to solve this problem, because they can remove heat from the IC chips or MEMS devices without involving any moving mechanical parts. TE materials and devices have been extensively investigated by researchers for the application of thermal-to-electrical energy conversion or solid-state cooling [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. However, the use of TE materials and devices is currently limited by their low efficiency. Nanostructured TE materials, such as nanolayered thin films and quantum-dot superlattices, have been found to have a thermoelectric merit significantly greater than the same bulk materials [17], due to the effect of quantum confinement on electrons and holes, as well as higher impedance to phonon transport in the nanoscale materials. The thermoelectric merit is defined as: ZT = S2σT/κ, where T is the absolute temperature, σ is the electrical conductivity, κ is the thermal conductivity, and S is the Seebeck coefficient (defined as voltage difference divided by temperature difference (ΔV/ΔT)). The figure of merit of a TE device can also be obtained by measuring the maximum temperature achieved in the device. The formula for calculating the ZT value of a TE device is: ZT = 2ΔTmax/T. It is challenging to characterize the nanoscale TE materials and accurately measure the three parameters simultaneously for finding the ZT value. On the other hand, in some TE material based devices, it is desired to frequently in-field monitor the ZT change of the TE materials in order to diagnose the device lifetime or quality degradation in use. To address these needs, two microstructures and one in-plane integrated TE device integrating temperature sensors and Sb2Te3 film, are proposed for on-chip sensing of the Seebeck Coefficient and ZT parameter (as shown in Figure 1, Figure 2 and Figure 3). To measure the cross-plane Seebeck coefficient of a TE film, the TE film is sandwiched between a diode-based temperature sensor and a Pt film temperature sensor (Figure 1). The cross-plane Seebeck coefficient is obtained by measuring the voltage difference and temperature difference between the top and bottom surface of the film. To measure the in-plane Seebeck coefficient of a TE film, the two ends of the TE film are located on the top of two diode-based temperature sensors (Figure 2). The in-plane Seebeck coefficient is obtained by measuring the voltage difference and temperature difference between the two ends of the film. To measure the ZT value of the in-plane integrated TE device, two diode-based temperature sensors are designed at the left side and the right side of the device (Figure 3). The ZT value is obtained by measuring the maximum temperature difference achieved in the TE device. These microstructures are fully compatible to IC or MEMS fabrication steps, and can be easily built in to any TE film based devices.


On-Chip Sensing of Thermoelectric Thin Film's Merit.

Xiao Z, Zhu X - Sensors (Basel) (2015)

(a) SEM image of an enlarged view on a diode temperature sensor; (b) SEM image of a fabricated TE device for measurement of the in-plane Seebeck coefficient of Sb2Te3 thin film, where two diode temperature sensors were fabricated under the two ends of the Sb2Te3 film and separated by an insulation layer of SiO2.
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sensors-15-17232-f002: (a) SEM image of an enlarged view on a diode temperature sensor; (b) SEM image of a fabricated TE device for measurement of the in-plane Seebeck coefficient of Sb2Te3 thin film, where two diode temperature sensors were fabricated under the two ends of the Sb2Te3 film and separated by an insulation layer of SiO2.
Mentions: Managing heat flux has been one of the most important technical challenges that the current integrated circuit (IC) or MEMS industry is facing, because the rising temperature limits the miniaturization of IC or MEMS devices and decreases their lifetime [1]. Solid-state thermoelectric (TE) cooling techniques are of great interest to solve this problem, because they can remove heat from the IC chips or MEMS devices without involving any moving mechanical parts. TE materials and devices have been extensively investigated by researchers for the application of thermal-to-electrical energy conversion or solid-state cooling [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. However, the use of TE materials and devices is currently limited by their low efficiency. Nanostructured TE materials, such as nanolayered thin films and quantum-dot superlattices, have been found to have a thermoelectric merit significantly greater than the same bulk materials [17], due to the effect of quantum confinement on electrons and holes, as well as higher impedance to phonon transport in the nanoscale materials. The thermoelectric merit is defined as: ZT = S2σT/κ, where T is the absolute temperature, σ is the electrical conductivity, κ is the thermal conductivity, and S is the Seebeck coefficient (defined as voltage difference divided by temperature difference (ΔV/ΔT)). The figure of merit of a TE device can also be obtained by measuring the maximum temperature achieved in the device. The formula for calculating the ZT value of a TE device is: ZT = 2ΔTmax/T. It is challenging to characterize the nanoscale TE materials and accurately measure the three parameters simultaneously for finding the ZT value. On the other hand, in some TE material based devices, it is desired to frequently in-field monitor the ZT change of the TE materials in order to diagnose the device lifetime or quality degradation in use. To address these needs, two microstructures and one in-plane integrated TE device integrating temperature sensors and Sb2Te3 film, are proposed for on-chip sensing of the Seebeck Coefficient and ZT parameter (as shown in Figure 1, Figure 2 and Figure 3). To measure the cross-plane Seebeck coefficient of a TE film, the TE film is sandwiched between a diode-based temperature sensor and a Pt film temperature sensor (Figure 1). The cross-plane Seebeck coefficient is obtained by measuring the voltage difference and temperature difference between the top and bottom surface of the film. To measure the in-plane Seebeck coefficient of a TE film, the two ends of the TE film are located on the top of two diode-based temperature sensors (Figure 2). The in-plane Seebeck coefficient is obtained by measuring the voltage difference and temperature difference between the two ends of the film. To measure the ZT value of the in-plane integrated TE device, two diode-based temperature sensors are designed at the left side and the right side of the device (Figure 3). The ZT value is obtained by measuring the maximum temperature difference achieved in the TE device. These microstructures are fully compatible to IC or MEMS fabrication steps, and can be easily built in to any TE film based devices.

Bottom Line: Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts.The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques.The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Alabama A&M University, Normal, AL 35762, USA. zhigang.xiao@aamu.edu.

ABSTRACT
Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques. Specifically, e-beam evaporation was used to grow the thermoelectric thin film of Sb2Te3 (100 nm thick). The Seebeck coefficient and the merit of the Sb2Te3 thin film were measured or determined. The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication.

No MeSH data available.


Related in: MedlinePlus