The growth of >100-?m-thick diamond layersadherent on aluminum nitride with low thermal boundaryresistance between diamond and AlN is presented in this work. The thermal barrier resistance was found to be in therange of 16 m2·K/GW, which is a large improvement on thecurrent state-of-the-art. While thickfilms failed to adhere onuntreated AlNfilms, AlNfilms treated with hydrogen/nitrogen plasma retained the thick diamond layers. Cleardifferences in?-potential measurement confirm surfacemodification due to hydrogen/nitrogen plasma treatment. An increase in non-diamond carbon in the initial layers ofdiamond grown on pretreated AlN is seen by Ramanspectroscopy. The presence of non-diamond carbon has minimal effect on the thermal barrier resistance. The surfaces studiedwith X-ray photoelectron spectroscopy revealed a clear distinction between pretreated and untreated samples. The surfacealuminum goes from a nitrogen-rich environment to an oxygen-rich environment after pretreatment. A clean interface betweendiamond and AlN is seen by cross-sectional transmission electron microscopy.

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