Differential Reflectance Spectroscopy in Analysis of Surfaces

摘要: Differential reflectance spectroscopy (DRS) is a surface analytical technique. It uses ultraviolet (UV), visible, or infrared (IR) light as probing medium. The interaction of with “strongly absorbing materials”, such metals, alloys, semiconductors, etc. occurs in the first 10–20 nm. Thus differential reflectometer probes 50–100 atomic layers into nontransparent solid surfaces. Because specific depth light, DRS fills gap between other techniques ion-scattering, Auger spectroscopy, and ESCA (electron for chemical analysis), which probe 1, 5, even 20 monolayers, X-ray diffraction (XRD) deep 1–50 µm bulk material. information gained by somewhat different from that obtained mentioned. A “differential reflectogram” reveals details about electron structure around Fermi surface. Specifically, instrument allows exact measurement energies electrons absorb photons they are raised higher, allowed energy states. Since each material has electron-band characteristic “interband transitions” serves means identifying these materials. Furthermore, investigation any shift energies, may be caused addition solute elements to solvent, transformations, lattice defects, ordering, like, provides deeper insight nature state. application is, course, not restricted strongly materials semiconductors. Its strength likewise been demonstrated identification characterization transparent semitransparent observed thin-film corrosion products on metal substrates. used scan two samples whose properties differ slightly. Thus, main advantage over conventional optical lies its ability eliminate undesirable influences oxides, windows, electrolytes, instrumental variations, owing No vacuum needed unless measurements UV desired. formation layer due environmental interactions can studied situ. fast: complete reflectogram, an automatic through visible IR region, accomplished 3 min.