Step-Controlled Epitaxial Growth of 4H-SiC and Doping of Ga as a Blue Luminescent Center

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Abstract
Homoepitaxial growth of 4H-SiC could be achieved at 1500°C on off-oriented 4H-SiC{0001} substrates by means of a vapor phase epitaxial method. Grown layers showed specular smooth surfaces on both (0001)Si and (0001̄)C faces. Doping of Ga during crystal growth was carried out and photoluminescence of grown layers was studied. Bluish-violet photoluminescence due to donor(N)-acceptor(Ga) pair recombination and recombination of a free electron with a hole at a Ga acceptor was observed. The emission attributed to the latter recombination process became dominant at high temperatures above 100 K. The luminescence of Ga-doped 4H-SiC was not quenched up to temperatures as high as 150 K, whereas the luminescence intensity of Al-doped 6H-SiC and 4H-SiC started to decrease at 70 and 85 K, respectively.