Peculiarities of phase transformations in SiC crystals and thin films with in-grown original defects

Abstract

Abstract. Phase transformations of SiC crystals and thin films with in-grown original defects have been studied. The analysis of absorption, excitation and low-temperature photoluminescence spectra testifies to formation of new micro-phases during the growth. The complex spectra can be decomposed into similar structure-constituting spectra shifted against each other on the energy scale. These spectra are indicative of formation of new nanophases. Taking into account the position of the short-wave edge in the zerophonon part of the SF-i spectra as well as the position of corresponding excitation spectra and placing them on the well-known linear dependence of the exciton gap (E gx ) on the percentage of hexagonally in different polytypic structures, one can obtain a hint to the percentage of hexagonally in the new metastable structures appearing in the 6H (33) matrix or in the growth process. The SF spectra are indicative of the appearance of these metastable structures.

Structure of photoluminescence DL-spectra and phase transformation in lightly doped SiC crystals and films

“…On the contrary, in the DL spectra both the zero-phonon part and phonon replica were present. As well as for the SF spectra [6], the fine structure of the zero-phonon part can be separated into two parts DL-I and DL-II. Decoding the DL spectrum shows that it comprises zerophonon parts -two linear group X and Y and their phonon replicas as one with LA, LO and local phonons with the energies (70 ± 1.0), (119 ± 1.0) and, (91 ± 1.0) meV, respectively.…”

“…[6]), we denominate them DL-I(X) and DL-II(Y). The fine structure of the DL spectra visible in the samples with different levels of impurities is shown in Fig.…”

“…Therefore, it couldn't sustain energetic stability of the given modification. Spectroscopy of the stacking faults and their detailed structure in the high purity SiC crystals was described in [5,6].…”

“…Defects in SiC crystals with a low level of impurities (with in-grown original defects) have been investigated in Ref [6,7].…”

“…The data from the photoluminescence, excitation and absorption spectra show similarity of different DL i spectra. However, the structure of SF spectra was discussed in details [5,6]. DL i spectra are still under investigation.…”