Nanostructures in lightly doped silicon carbide crystals with polytypic defects

Abstract

Abstract. In this work, photoluminescence spectra of lightly doped SiC crystals with ingrown original defects are reported. , N D  110 18 cm -3 were investigated. The analysis of absorption, excitation and low temperature photoluminescence spectra suggests formation of a new micro-phase during the growth process and appearance of the deep-level (DL) spectra. The complex spectra of the crystals can be decomposed into the so-called DL i (i = 1, 2, 3, 4) spectra. The appearance of the DL i spectrum is associated with formation of new nano-phases. Data of photoluminescence, excitation and absorption spectra show the uniformity of different DL i spectra. Structurally, the general complexity of the DL i spectra correlated with the degree of disorder of the crystal and was connected with onedimensional disorder, the same as in the case of the stacking fault (SF i ) spectra. The DL i spectra differ from SF i spectra and have other principles of construction and behavior. The DL i spectra are placed on a broad donor-acceptor pairs emission band in crystals with higher concentrations of non-compensated impurities. The excitation spectra for the DL i and SF i spectra coincide and indicate formation of nanostructures 14H 1 4334, 10H 2 55, 14H 2 77, 8H44.

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

“…Peculiarities of the Laue patterns of the D-layers in 6H-SiC crystals are the same as for the 3C-SiC crystals after phase transformation [9]. Pure samples with the SF-i and DL-i series, show a linear dependence of intensity of the DL-i spectra on the impurity concentration [9].…”

“…Pure samples with the SF-i and DL-i series, show a linear dependence of intensity of the DL-i spectra on the impurity concentration [9].…”

“…For the absorption spectra of DL samples [9], it was shown that absorption is spread far to the lower energy region relative to General panorama of the PL spectra of the samples consists of a certain set of the SF-spectra with different intensities. Sometimes, it is peculiar to the different parts of the same crystal.…”

Nanograin boundaries and silicon carbide photoluminescence

“…We studied low temperature spectra by using techniques described early [7]. For this experiment, we selected lumpy, blocky SiC crystals and crystals with steps of growth.…”

“…Experimental results and theoretical calculations showed that the luminescence of different polytypes strongly influenced by defects [1][2][3]. The luminescence spectra [4,5] of SiC crystals and films with stacking faults (SF i ) in highpurity SiC [2] and with deep level (DL i ) [6][7][8][9] in lightly doped SiC reflect formation of intermediate metastable phases during 3C↔6H transitions. SF i and DL i spectra hand-in-hand follow the structure transformations.…”