Raman spectroscopy, semiconductor doped

For the visible and near-ultraviolet portions of the spectmm, tunable dye lasers have commonly been used as the light source, although they are being replaced in many appHcation by tunable soHd-state lasers, eg, titanium-doped sapphire. Optical parametric oscillators are also developing as useful spectroscopic sources. In the infrared, tunable laser semiconductor diodes have been employed. The tunable diode lasers which contain lead salts have been employed for remote monitoring of poUutant species. Needs for infrared spectroscopy provide an impetus for continued development of tunable infrared lasers (see Infrared technology and RAMAN spectroscopy). 

A similar result has been found using Raman spectroscopy of core-shell nanocrystals. Like XRD, Raman spectroscopy has also been widely employed to study doping of bulk semiconductors (110-112) but so far has only rarely been applied to doped semiconductor nanocrystals (70). Analogous to Vegard s law, shifts in lattice Raman vibrational energies have been found to occur with increasing dopant concentration in both the bulk and nanocrystalline materials. 

Rapid advances in semiconductor techrwlogy, including thin film formation by deposition, interface preparation or microstructuring, demand characterization techniques that provide understanding of the fundamental processes involved, including information on structural order—disorder and spatial inhomogeneity. Raman spectroscopy is used both in process control and quality assessment [34]. Typical examples of semiconductor applications are composition determination, analysis of crystal structure, surface and interface analysis, phase determination, doping, point defects, temperature influence and mechanical stress. 

---