Abstract
The Si(0001) face and C(000-1) face dependences on growth pressure of epitaxial graphene (EG) grown on 4H-SiC substrates by ethene chemical vapor deposition (CVD) was studied using atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). AFM revealed that EGs on Si-faced substrates had clear stepped morphologies due to surface step bunching. However, This EG formation did not occur on C-faced substrates. It was shown by μ-Raman that the properties of EG on both polar faces were different. EGs on Si-faced substrates were relatively thinner and more uniform than on C-faced substrates at low growth pressure. On the other hand, D band related defects always appeared in EGs on Si-faced substrates, but they did not appear in EG on C-faced substrate at an appropriate growth pressure. This was due to the μ-Raman covering the step edges when measurements were performed on Si-faced substrates. The results of this study are useful for optimized growth of EG on polar surfaces of SiC substrates.
Highlights
Epitaxial growth of graphene (EG) is more facile in area and layer thickness control [1] than the classic exfoliation of highly oriented pyrolytic graphite crystals (HOPG) [2]
After HOPG was demonstrated by Novoselov K.S. and Geim A.K. [2], Berger C. [8] conducted epitaxial graphene (EG) on semi-insulting silicon carbide (SI SiC) by using sublimation of silicon atoms from SI SiC surface at high temperature (S-EG)
S-EG based on SiC wafer is high energy-consumption and expensive since the thermal decomposition is performed at a temperature higher than 1600 ̋ C using the expensive commercial available SiC wafer as the starting material
Summary
Epitaxial growth of graphene (EG) is more facile in area and layer thickness control [1] than the classic exfoliation of highly oriented pyrolytic graphite crystals (HOPG) [2]. EG growth on SiC by using chemical vapor deposition (CVD) has been developed [18] In this growth process, graphene is synthesized by thermal decomposition of carbon precursor instead of sublimation of surface Si atoms from SiC substrate. Graphene is synthesized by thermal decomposition of carbon precursor instead of sublimation of surface Si atoms from SiC substrate By both using carbon precursor and controlling the dynamic flow in the chamber [11], various reaction parameters in affecting the number of layers and the defect degree of the synthesized graphene have been reported, such as annealing time, heating ramp rates [19], hydrogen partial pressure [20], and growth time [21]. SiC by both adjusting the flow rate of the carbon precursor and the chamber pressure In this way, we are able to investigate the growth nature of CVD EG on both polar faces of 4H-SiC
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