Characterization of wide-band-gap semiconductors (GaN, SiC) by defect-selective etching and complementary methods

Two defect-selective etching approaches used for revealing and analysis of defects in wide-band-gap semiconductors (GaN, SiC) are described in detail: (i) orthodox etching in molten salts (KOH, NaOH) and hot acids (H2SO4,H3PO4) and (ii) electroless photo-etching (photoelectrochemical or PEC) in aqueous solutions of KOH. Characteristic features of these two techniques, their reliability and limitation in revealing different types of defects (dislocations, stacking faults, micro-defects and electrically active chemical non-homogeneities) will be discussed. Examples of the use of both etching approaches to reveal defects in bulk and epitaxial layers of different crystallographic orientation are given. Numerous references to previous work on calibration of the etch features by means of TEM, X-ray diffraction, Raman and PL methods are cited.