Transmission of phonons through grain boundaries in diamond films
| Autor: | Clifford J. Robinson, Donald T. Morelli, Ctirad Uher |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Applied Physics Letters. 62:1085-1087 |
| ISSN: | 1077-3118 0003-6951 |
| Popis: | With the advent of new growth techniques, research on the properties of diamond has undergone a rebirth in recent years. The capability of producing very high quality polycrystalline films has greatly enhanced the prospects of exploiting the extreme physical properties of this substance. One area of great interest has been the thermal conductivity K of synthetically produced diamond. Vapordeposited material is now made routinely with room temperature thermal conductivities up to 85% that of bulk single crystals. It is not yet clear, however, what processes limit the conductivity to values below that of single crystal material. Some time ago, it was recognized”2 that the polycrystalline nature of the film morphology could provide some limitation to the thermal conductivity at and even above room temperature. More recently, detailed studies of the anisotropy of the thermal conductivity3 as well as a through-the-thickness gradient in K’,~ have provided some indirect evidence of the influence of grain boundary scattering. On the other hand, it has also been shown6 that very low levels of defects within the grains, most likely associated with small concentrations of nondiamond carbon, are capable of strongly degrading the thermal conductivity over the temperature range 20-300 K. Separation of the influence of grain boundaries and other defects is complicated by the fact that samples with smaller grains usually have more defects since the latter tend to be concentrated at grain boundaries7 One can, in principle, differentiate to some extent between the effects of intragrain defects and grain boundaries on the heat conduction by measuring K |
| Databáze: | OpenAIRE |
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