17406
Twisted bilayer graphene can be obtained by ( i ) thermal decomposition of SiC ; ( ii ) chemical vapor deposition ( CVD ) on metal catalysts ; ( iii ) folding graphene ; or ( iv ) stacking graphene layers one atop the other , the latter of which suffers from interlayer contamination .
 Chemical: graphene; Chemical: SiC; Chemical: graphene; Chemical: graphene
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: graphene; Chemical: SiC; Chemical: graphene; Chemical: graphene