Temperature Dependence of Raman Scattering in 4H-SiC Films under Different Growth Conditions**Supported by the National Natural Science Foundation of China under Grant Nos 61176085, 11474365 and 61377055, the Department of Education of Guangdong Province under Grant No gjhz1103, and the Open-Project Program of the State Key laboratory of Opto-Electronic Material and Technologies of Sun Yatsen University.

Abstract

The microRaman scattering of 4H-SiC films, fabricated by low pressure chemical vapor deposition under different growth conditions, is investigated at temperatures ranging from 80K to 550K. The effects of growth conditions on E2(TO), E1(TO) and A1(LO) phonon mode frequencies are negligible. The temperature dependences of phonon linewidth and lifetime of E2(TO) modes are analyzed in terms of an anharmonic damping effect induced by thermal and growth conditions. The results show that the lifetime of E2(TO) mode increases when the quality of the sample improves. Unlike other phone modes, Raman shift of A1 (longitudinal optical plasma coupling (LOPC)) mode does not decrease monotonously when the temperature increases, but tends to blueshift at low temperatures and to redshift at relatively high temperatures. Theoretical analyses are given for the abnormal phenomena of A1(LOPC) mode in 4H-SiC.