Criteria for Cross-Plane Dominated Thermal Transport in Multilayer Thin Film Systems During Modulated Laser Heating

Pump-probe transient thermoreflectance (TTR) techniques are powerful tools for measuring the thermophysical properties of thin films, such as thermal conductivity, Λ, or thermal boundary conductance, G. This paper examines the assumption of one-dimensional heating on, Λ and G, determination in nanostructures using a pump-probe transient thermoreflectance technique. The traditionally used one-dimensional and axially symmetric cylindrical conduction models for thermal transport are reviewed. To test the assumptions of the thermal models, experimental data from Al films on bulk substrates (Si and glass) are taken with the TTR technique. This analysis is extended to thin film multilayer structures. The results show that at 11 MHz modulation frequency, thermal transport is indeed one dimensional. Error among the various models arises due to pulse accumulation and not accounting for residual heating.

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Dimensionality Analysis of Thermal Transport in Multilayer Thin Film Systems

Volume 12: Micro and Nano Systems, Parts A and B ◽

10.1115/imece2009-12238 ◽

2009 ◽

Author(s):

Patrick E. Hopkins ◽

Justin R. Serrano ◽

Leslie M. Phinney ◽

Sean P. Kearney ◽

Thomas W. Grasser ◽

...

Keyword(s):

Thin Film ◽

Thermal Transport ◽

Modulation Frequency ◽

3D Models ◽

Dimensional Error ◽

Pump Probe ◽

One Dimensional ◽

Thermal Boundary Conductance ◽

Dimensionality Analysis ◽

Thermal Conductivity Λ

Pump-probe transient thermoreflectance (TTR) techniques are powerful tools for measuring thermophysical properties of thin films, such as thermal conductivity, Λ, or thermal boundary conductance, G. This paper examines the assumption of one-dimensional heating on Λ and G determination in nanostructures using a pump-probe transient thermoreflectance technique. The traditionally used one dimensional and radial (3D) models are reviewed. To test the assumptions of the thermal models, experimental data from Al films on bulk substrates (Si and glass) are taken with the TTR technique. This analysis is extended to thin film multilayer structures. Results show that at 11 MHz modulation frequency, thermal transport is indeed one dimensional. Error among the various models arises due to pulse accumulation and not accounting for residual heating.

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Thermal Models for Determining Thermal Conductivity and Thermal Boundary Conductance Using Pump-Probe Thermoreflectance Techniques

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment ◽

10.1115/ht2009-88269 ◽

2009 ◽

Author(s):

Patrick E. Hopkins ◽

Justin R. Serrano ◽

Leslie M. Phinney

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Probe Signal ◽

Pump Probe ◽

Thermal Models ◽

Thermal Boundary Conductance ◽

Advantages And Disadvantages ◽

Heating Event ◽

Lock In ◽

Thermal Conductivity Λ

Pump-probe transient thermoreflectance (TTR) techniques are powerful tools for measuring thermophysical properties of thin films, such as thermal conductivity, Λ, or thermal boundary conductance, G. TTR experimental setups rely on lock-in techniques to detect the response of the probe signal relative to the pump heating event. The temporal decays of the lock-in signal are then compared to thermal models to deduce the Λ and G in and across various materials. There are currently two thermal models that are used to relate the measured signals from the lock-in to the Λ and G in the sample of interest. In this work, the thermal models, their assumptions, and their ranges of applicability are compared. The advantages and disadvantages of each technique are elucidated from the results of the thermophysical property measurements.

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Effects of the Multilayer Structure on the Responsivity of Pyroelectric Thin Film Detectors

MRS Proceedings ◽

10.1557/proc-360-435 ◽

1994 ◽

Vol 360 ◽

Author(s):

Zhu Jianguo ◽

Xiao Dingquan ◽

Qian Zhenghong ◽

Zhang Wen ◽

Du Siaosong

Keyword(s):

Thin Film ◽

Thin Films ◽

Integrated Circuit ◽

Multilayer Structure ◽

Modulation Frequency ◽

Flow Equation ◽

One Dimensional ◽

The One ◽

Direct Incorporation ◽

Room Temperature Operation

AbstractPyroelectric thin film detectors have advantages of wavelength independent sensitivity, room temperature operation and direct incorporation with integrated circuit amplifiers. Pyroelectric thin films with good quality have be prepared by many advanced thin film technologies [1-2]. The responsivity of pyroelectric thin film detectors is dependent on the thermal properties of the substrate, on which pyroelectric thin film detectors are prepared. The heat conduction in the detectors was investigated using the one-dimensional heat flow equation and the expressions describing the detectors performance were derived for pyroelectric thin films detectors with multilayer structure. The numerical simulation showed that the pyroelectric thin film detectors need effective heat isolation. If the air gap could be the heat isolation layer, which is between the bottom electrode and substrate, the iesponsivity of detectors would be higher than that of detectors which have no heat isolation in certain modulation frequency range.

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