Influence of the microstructure on the thermal properties of thin polycrystalline diamond films

Verhoeven, Hans; Flöter, A.; Reiss, Harald; Zachai, R.; Wittorf, D.; Jäger, W.

doi:10.1063/1.119886

Cited by 40 publications

(22 citation statements)

References 9 publications

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“…4). This values are in the ranges reported by other authors for c-NCD layers of similar thicknesses ($180-500 W/mK), [21][22][23] while the diamond/substrate TBR is similar to the one reported in Ref. 24 for c-NCD on Si.…”

Section: -39supporting

confidence: 77%

“…14 To determine the thermal characteristics in the near nucleation region, measuring the j of ultra-thin layers of columnar nano-crystalline diamond (c-NCD) is needed; however, this is a challenging task, which is mostly performed with transient measurements. [20][21][22][23][24][25] Nevertheless, these transient techniques are indirect methods having access only to the thermal diffusivity, which requires a complex data analysis for extracting the thermal conductivity. As a result, in-plane thermal conductivities ranging from 20 W/ mK (Refs.…”

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confidence: 99%

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Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

Anaya

Rossi

Alomari

et al. 2015

Applied Physics Letters

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The thermal transport in polycrystalline diamond films near its nucleation region is still not well understood. Here, a steady-state technique to determine the thermal transport within the nano-crystalline diamond present at their nucleation site has been demonstrated. Taking advantage of silicon nanowires as surface temperature nano-sensors, and using Raman Thermography, the in-plane and cross-plane components of the thermal conductivity of ultra-thin diamond layers and their thermal barrier to the Si substrate were determined. Both components of the thermal conductivity of the nano-crystalline diamond were found to be well below the values of polycrystalline bulk diamond, with a cross-plane thermal conductivity larger than the in-plane thermal conductivity. Also a depth dependence of the lateral thermal conductivity through the diamond layer was determined. The results impact the design and integration of diamond for thermal management of AlGaN/GaN high power transistors and also show the usefulness of the nanowires as accurate nano-thermometers.

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Section: -39supporting

confidence: 77%

mentioning

confidence: 99%

Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

Anaya

Rossi

Alomari

et al. 2015

Applied Physics Letters

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“…A few inconsistent results are available in the literature about the in-plane thermal transport in the first microns of polycrystalline diamond showing values ranging from a few W/mK up to 800 W/mK for layers thicknesses below 2 µm. [13,14,15,16,17,18,19,20,21,22,23, 24] Also 25 a strong inhomogeneity of the in-plane thermal conductivity through the diamond films has been reported, [11,12,21,22,24] although mostly for films larger 2 than a few micrometer thickness, due to challenges in measuring the thermal properties of very thin diamond films. Therefore a clear description of the heat transport in the complex near nucleation region of polycrystalline diamond is 30 still lacking.…”

Section: Introductionmentioning

confidence: 99%

Control of the in-plane thermal conductivity of ultra-thin nanocrystalline diamond films through the grain and grain boundary properties

et al. 2016

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The in-plane thermal conductivity of polycrystalline diamond near its nucleation site, which is a key parameter to an efficient integration of diamond in modern high power AlGaN/GaN high electron mobility devices, has been studied. By controlling the lateral grain size evolution through the diamond growth conditions it has been possible to increase the in-plane thermal conductivity of the polycrystalline diamond film for a given thickness. Besides, the in-plane thermal conductivity has been found strongly inhomogeneous across the diamond films, being also possible to control this inhomogeneity by the growth conditions. The experimental results has been explained through a combined effect of the phonon mean free path confinement due the grain size and the quality of the grain/grain interfaces, showing that both effects evolve with the grain expansion and are dependant on the diamond growth conditions. This analysis shows how the thermal transport in the near nucleation region of polycrystalline diamond can be controlled, which ultimately opens the door to create ultra-thin layers with a engineered thermal conductivity, ranging from a few W/mK to a few hundreds of W/mK.

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“…However, due to the difficulty of heteroepitaxial growth of single-crystalline diamond on foreign substrates, most applications utilize CVD-deposited poly-crystalline diamond films. The thermal properties of such films are strongly dependent on the microstructure [2], and k spans over two orders of magnitude, depending on the geometry of the grains and concentration of defects and impurities, which in turn are function of the growth process [3].…”

Section: Introductionmentioning

confidence: 99%

Thermal analysis of submicron nanocrystalline diamond films

Rossi

Alomari

Zhang

et al. 2013

Diamond and Related Materials

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The thermal properties of sub-µm nanocrystalline diamond films in the range 0.37-1.1 µm grown by hot filament CVD, initiated by bias enhanced nucleation on a nm-thin Si-nucleation layer on various substrates, have been characterized by scanning thermal microscopy. After coalescence, the films have been outgrown with a columnar grain structure. The results indicate that even in the sub-µm range, the average thermal conductivity of these NCD films approaches 400 Wm -1 K -1 . By patterning the films into membranes and step-like mesas, the lateral and the vertical component of the thermal conductivity, k lateral and k vertical , have been isolated showing an anisotropy between vertical conduction along the columns, with k vertical ≈1000 Wm -1 K -1 , and a weaker lateral conduction across the columns, with k lateral ≈ 300 Wm -1 K -1 .

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Influence of the microstructure on the thermal properties of thin polycrystalline diamond films

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Cited by 40 publications

References 9 publications

Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

Control of the in-plane thermal conductivity of ultra-thin nanocrystalline diamond films through the grain and grain boundary properties

Thermal analysis of submicron nanocrystalline diamond films

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