Scanning thermal microscopy

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SEM images of a conventional SThM tip based on an Au–Cr thermocouple.[1]
Thermal conductivity image of a gold letter E on sapphire. White circles indicate features that do not correlate with the AFM topography. (d) PL image of the AFM cantilever end and tip where the diamond nanocrystal appears as the bright spot. (e) Zoomed PL image of the N-V center in d.[2]

Scanning thermal microscopy (SThM) is a type of

H. Kumar Wickramasinghe in 1986.[3]

Applications

SThM allows thermal measurements at the nano-scale. These measurements can include: temperature, thermal properties of materials,

glass transition temperature, latent heat, enthalpy
, etc. The applications include:

Technique

SThM requires the use of specialized probes. There are two types of thermal probes: Thermocouple probes where the probe temperature is monitored by a thermocouple junction at the probe tip and resistive or bolometer probes where the probe temperature is monitored by a thin-film resistor at probe tip. These probes are generally made from thin dielectric films on a silicon substrate and use a metal or semiconductor film bolometer to sense the tip temperature. Other approaches, using more involved micro machining methods, have also been reported.[20] In a bolometer probe the resistor is used as a local heater and the fractional change in probe resistance is used to detect the temperature and/or the thermal conductance of the sample.[15] When the tip is placed in contact with the sample, heat flows from the tip to sample. As the probe is scanned, the amount of heat flow changes. By monitoring the heat flow, one can create a thermal map of the sample, revealing spatial variations in thermal conductivity in a sample. Through a calibration process, the SThM can reveal the quantitative values of thermal conductivity.[21] Alternately the sample may be actively heated, for example a powered circuit, to visualize the distribution of temperatures on the sample.

Tip-sample heat transfer can include

  • Solid-solid conduction. Probe tip to sample. This is the transfer mechanism which yields the thermal scan.
  • Liquid-liquid conduction. When scanning in non-zero humidity, a liquid meniscus forms between the tip and sample. Conduction can occur through this liquid drop.
  • Gas conduction. Heat can be transferred through the edges of the probe tip to the sample.

References

  1. PMID 28198467
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  2. PMID 26584676
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  3. doi:10.1063/1.97288.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  4. ^
    doi:10.1016/S0924-4247(03)00026-8.{{cite journal}}: CS1 maint: multiple names: authors list (link
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  5. ^
    doi:10.1109/84.911085
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  6. doi:10.1116/1.588626
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  7. S2CID 15455318
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  8. ^
    S2CID 250787874
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  9. doi:10.1063/1.116074
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  10. S2CID 42233076
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  11. hdl:2027.42/69814.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  12. S2CID 93359289
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  13. doi:10.1147/rd.443.0323
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  14. doi:10.1016/S0925-4005(00)00554-2
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  15. ^ a b Lee, J-H. et al. International Workshop on Thermal Investigations of ICs and Systems (THERMINIC 2002), Madrid, Spain, October 2002, pp. 111–116.
  16. ^ Hendarto, E.; et al. (2005). Proceedings 43rd Annual IEEE International Reliability Physics Symposium: 294–299
  17. S2CID 9471815.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  18. doi:10.1063/1.2171929
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  19. S2CID 98802503
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  20. doi:10.1109/16.641353.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  21. doi:10.1093/nsr/nwx074
    .

External links

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