| Zugriffsnummer | 16687 |
| Dokumenttyp | Buchartikel |
| Sprache | Englisch |
| Titel | Thermal characterization of diamond |
| Autor(in); Institution |
Reichling, M.; Universität München, München, GERMANY
Hartmann, Jürgen; 7.21, Temperaturstrahlung, PTB-Berlin
|
| Quelle/Jahr | Properties, growth and applications of diamond:(2001), 55 - 65 |
| Schriftenreihe | EMIS datareview series: 26 |
| Herausgeber(in) |
Nazaré, Maria Helena
|
| ISBN | 0-85296-785-3 |
| Verlag | London: INSPEC |
| Freie Schlagworte | Thermalconductivity ; diamond ; Wärmeleitfähigkeit ; Diamant |
| Zusammenfassung | Thermal characterisation of diamond is one of the key issues in assessing material quality since thermal parameters are strongly related to other features like isotopic constitution, defect content and microstructure (see section A3.3). Hence, the macroscopic thermal conductivity can often be taken as a figure-of-merit for diamond quality relevant for industrial applications. Determining thermal conductivity of diamond materials does principally not require other techniques than those used for thermal assessment of more common materials and the standard methods as well as their application to diamond have been described in detail in rather complete review articles. Recent advancements in methodology have mainly been focused on thermal microscopy for measuring conductivity in extremely small volumes and finally single grains of polycrystalline material and to quantitatively determine resistances across thermal barriers related to grain boundaries in thin films. In this survey we summarise the main features of the standard techniques and briefly review the technology of quantitative thermal microscopy. It is difficult to precisely control and measure heat flow and radiation and, hence, thermal measurements generally yield only a rather limited precision; this fully applies also to measurements on diamond materials. An accuracy of a few per cent has to be regarded as excellent while the precision of most measurements is on a 5 to 10 % level or below. As demonstrated by a recent Round Robin test, this especially applies to the characterisation of polycrystalline thin films where measurements may be strongly affected by the presence of a substrate, sample inhomogeneities, microstructure and subtle experimental details. This test also revealed significant differences between results obtained on the same sample. Hence, thermal characterisation of diamond materials is presently well developed for a rough quality assessment, however, the precise determination of thermal parameters by standardised routine procedures is not yet available. The choice of the method for thermal characterisation of a specific sample is, therefore, mostly not motivated by the obtainable level of accuracy but by other criteria related to the characteristics of the specimen, the desired information, the temperature range and practical or economical considerations (for detailed selection tables see Ref. Fehler! Textmarke nicht definiert.). Steady state techniques as described in section B do mostly not require sophisticated equipment and analysis and are normally applied to large bulk sample. Dynamic methods described in section C allow the restriction of the measured heat flow to a small volume and are, therefore, well suited for small samples and thin films. Heating of the sample can conveniently be provided by pulsed or modulated laser light what led to the development of photothermal techniques treated in section D. Their strength is the non-contact determination of thermal parameters. Utmost resolution is obtained by photothermal microscopy as reviewed in section E. |
