Thermal resistance and electrical insulation of thin low-temperature-deposited diamond films

Heat conduction in novel electronic films influences the performance and reliability of micromachined transistors, lasers, sensors, and actuators. This article reviews experimental and theoretical research on heat conduction in single-crystal semiconducting and superconducting films and superlattices, polycrystalline diamond films, and highly disordered organic and oxide films. The thermal properties of these films can differ dramatically from those of bulk samples owing to the dependence of the material structure and purity on film processing conditions and to the scattering of heat carriers at material boundaries. Predictions and data show that phonon scattering and transmission at boundaries strongly influence the thermal conductivities of single-crystal films and superlattices, although more work is needed to resolve the importance of strain-induced lattice defects. For polycrystalline films, phonon scattering on grain boundaries and associated defects causes the thermal conductivity to be strongly anisotropic and nonhomogeneous. For highly disordered films, preliminary studies have illustrated the influences of impurities on the volumetric heat capacity and, for the case of organic films, molecular orientation on the conductivity anisotropy. More work on disordered films needs to resolve the interplay among atomic-scale disorder, porosity, partial crystallinity, and molecular orientation.

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“…diamond film with k n = 600 W m −1 K −1 investigated by Verhoeven et al (21) on a silicon substrate.…”

Section: Metrologymentioning

confidence: 99%

“…The lateral thermal conductivity of films on substrates has been measured using the transient thermal grating technique (21,49,50), which is depicted in Figure 4b. Pulsed laser radiation interferes on the sample surface, yielding a harmonic spatial variation of energy absorption.…”

Section: Metrologymentioning

confidence: 99%

Heat Conduction in Novel Electronic Films

Goodson

1999

Annu. Rev. Mater. Sci.

163

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“…3(b)]; this variation may be related to the slightly inhomogeneous initial seeding conditions or different initial microstructual disorders. 46,47 Figure 3(c) shows j Dia as a function of temperature. All samples exhibit a negligible temperature dependence.…”

mentioning

confidence: 99%

Thermal characterization of polycrystalline diamond thin film heat spreaders grown on GaN HEMTs

Zhou

Ramaneti

Anaya

et al. 2017

Applied Physics Letters

113

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Polycrystalline diamond (PCD) was grown onto high-k dielectric passivated AlGaN/GaN-on-Si high electron mobility transistor (HEMT) structures, with film thicknesses ranging from 155 to 1000 nm. Transient thermoreflectance results were combined with device thermal simulations to investigate the heat spreading benefit of the diamond layer. The observed thermal conductivity (κDia) of PCD films is one-to-two orders of magnitude lower than that of bulk PCD and exhibits a strong layer thickness dependence, which is attributed to the grain size evolution. The films exhibit a weak temperature dependence of κDia in the measured 25–225 °C range. Device simulation using the experimental κDia and thermal boundary resistance values predicts at best a 15% reduction in peak temperature when the source-drain opening of a passivated AlGaN/GaN-on-Si HEMT is overgrown with PCD.

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“…Large discrepancies are observed for experimental conductance measured at the tungsten-diamond interface and reported values scale from 40 MW·m −2 ·K − 1 to 200 MW·m −2 ·K − 1 [19,20]. It has been shown that this conductance is very dependent on the surface properties (as roughness and crystalline orientation), on the deposition method and on the heat treatment applied [21][22][23]. In this model, a mean thermal boundary conductance of 100 MW·m −2 ·K −1 is assumed to represent the interface between a tungsten layer and a smooth single crystal diamond surface.…”

Section: Thermal Boundary Resistancementioning

confidence: 97%

Nanofocus diamond X-ray windows: Thermal modeling of nano-sized heat source systems

Delfaure

Mazellier

Tranchant

et al. 2015

Diamond and Related Materials

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a b s t r a c tAn analytical thermal model is proposed to study heat transfers occurring at high power density in X-ray tubes with micron to submicron sized source. The use of a simple analytical approach instead of a complex numerical simulation allows readily modeling of more and more challenging systems such as multi-source X-ray tubes. By significantly reducing the computing time, it enables a wider parameter range evaluation for engineering phase. We focused our work on tubes integrating a transmission window that is mainly edge-cooled. Our approach can be generally used in cylindrical lateral heat spreaders with distributed small sized source systems. The model enables an efficient estimation of temperature distributions for a large range of parameters and source designs and is, for instance, wellsuited to described nanosized heat source systems. It is developed from an electrostatic analogy with the point charge particle model and uses of a series of virtual sources. A multiscale resolution of the heat equation is proposed, hence providing the temperature distribution at any point within the whole system. Moreover, the non-linearity of equations caused by temperature-dependent thermal conductivities is solved by using Kirchhoff's transformation, giving a more realistic approach of heat conduction in diamond X-ray windows, where temperature in excess of 1000°C can be encountered. The influence of convective and radiative transfers has been discussed and the physical accuracy of the predicted temperature is controlled by adjusting the number of virtual sources of the model.

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Thermal resistance and electrical insulation of thin low-temperature-deposited diamond films

Cited by 23 publications

References 7 publications

Heat Conduction in Novel Electronic Films

Heat Conduction in Novel Electronic Films

Thermal characterization of polycrystalline diamond thin film heat spreaders grown on GaN HEMTs

Nanofocus diamond X-ray windows: Thermal modeling of nano-sized heat source systems

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