| Summary: | We report on experimental investigation of thermal contact resistance, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>R</mi><mi>C</mi></msub></mrow></semantics></math></inline-formula>, of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>S</mi><mi>q</mi></msub></mrow></semantics></math></inline-formula>. It is found that the thermal contact resistance depends on the graphene loading, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, non-monotonically, achieving its minimum at the loading fraction of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ξ</mi><mo> </mo><mo>~</mo><mn>15</mn><mo> </mo><mrow><mi>wt</mi><mo>%</mo></mrow></mrow></semantics></math></inline-formula>. Decreasing the surface roughness by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>S</mi><mi>q</mi></msub><mo>~</mo><mn>1</mn><mrow><mo> </mo><mi mathvariant="sans-serif">μ</mi><mi mathvariant="normal">m</mi></mrow></mrow></semantics></math></inline-formula> results in approximately the factor of ×2 decrease in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mrow><mi>T</mi><mi>I</mi><mi>M</mi></mrow></msub></mrow></semantics></math></inline-formula>, thermal contact resistance, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>R</mi><mi>C</mi></msub></mrow></semantics></math></inline-formula>, and the total thermal resistance of the thermal interface material layer on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>S</mi><mi>q</mi></msub></mrow></semantics></math></inline-formula> can be utilized for optimization of the loading fraction of graphene for specific materials and roughness of the connecting surfaces. Our results are important for the thermal management of high-power-density electronics implemented with diamond and other wide-band-gap semiconductors.
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