Time-domain thermoreflectance (TDTR) is a pump-probe technique frequently applied to measure the thermal transport properties of bulk materials, nanostructures, and interfaces. One of the limitations of TDTR is that it can only be employed to samples with a fairly smooth surface. For rough samples, artifact signals are collected when the pump beam in TDTR measurements is diffusely scattered by the rough surface into the photodetector, rendering the TDTR measurements invalid. In this paper, we systemically studied the factors affecting the artifact signals due to the pump beam leaked into the photodetector and thus established the origin of the artifact signals. We find that signals from the leaked pump beam are modulated by the probe beam due to the phase rotation induced in the photodetector by the illumination of the probe beam. As a result of the modulation, artifact signals due to the leaked pump beam are registered in TDTR measurements as the out-of-phase signals. We then developed a simple approach to eliminate the artifact signals due to the leaked pump beam. We verify our leak-pump correction approach by measuring the thermal conductivity of a rough InN sample, when the signals from the leaked pump beam are significant. We also discuss the advantages of our new method over the two-tint approach and its limitations. Our new approach enables measurements of the thermal conductivity of rough samples using TDTR.
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June 2016
Research Article|
June 03 2016
Understanding and eliminating artifact signals from diffusely scattered pump beam in measurements of rough samples by time-domain thermoreflectance (TDTR)
Bo Sun
;
Bo Sun
1Department of Mechanical Engineering,
National University of Singapore
, 9 Engineering Drive 1, Singapore
117576
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Yee Kan Koh
Yee Kan Koh
a)
1Department of Mechanical Engineering,
National University of Singapore
, 9 Engineering Drive 1, Singapore
1175762Centre of Advanced 2D Materials,
National University of Singapore
, Singapore
117542
Search for other works by this author on:
a)
Author to whom correspondence should be addressed. Electronic mail: mpekyk@nus.edu.sg
Rev. Sci. Instrum. 87, 064901 (2016)
Article history
Received:
February 23 2016
Accepted:
May 12 2016
Citation
Bo Sun, Yee Kan Koh; Understanding and eliminating artifact signals from diffusely scattered pump beam in measurements of rough samples by time-domain thermoreflectance (TDTR). Rev. Sci. Instrum. 1 June 2016; 87 (6): 064901. https://doi.org/10.1063/1.4952579
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