Characterization of GaN and Related Nitrides by Raman Scattering

Raman scattering is one of the standard optical characterization techniques for both lattice and electronic properties of semiconductor materials. Compared with other standard spectroscopic techniques, Raman scattering characterization has various merits; it is in principle nondestructive, and contactless, and it requires no special sample preparation such as thinning or polishing. When a standard Raman microscope is employed with common visible lasers, the probe laser beam is focused to a diameter of ~ 1 μm, which roughly gives the lateral resolution of the measurement. Since GaN and related compounds including their alloys (hereafter referred to as the nitrides) are in many cases transparent to common visible lasers, the depth resolution is somewhat worse than the lateral one; however, a depth resolution similar to the lateral one can be obtained if a suitable optical setup such as confocal arrangement is used.