Thermal conduction through diamond - silicon heterostructures

The interest to silicon-diamond structures was recently renewed motivated by industry´s needs for composite substrates and better thermal management. In this work we investigated thermal conductivity and thermal boundary resistance (TBR) of ultrananocrystalline (UNCD) and microcrystalline diamond (MCD) films on silicon. The measurements were carried out using the transient plane source (TPS) technique. It was found that most of the silicon-synthetic heterostructures are rather resistive thermally with the TBR values of up to ~10^-6 m²K/W at room temperature. We established an importance of the trade-off between the structures characterized by the ultra-small diamond grain size with smooth silicon-diamond interface and those with larger grain size but rougher interface. It is shown that composite Si/Diamond wafers are promising at the elevated temperatures characteristic for operation of state-of-art electronic devices. The knowledge of TBR and heat conduction through silicon - diamond heterostructures is important for further development of composite substrates for electronic and optoelectronic industries.