25997
In addition , a waveguide mechanism due to different refractive indices of three epilayers enhances the guided optical field on the ZnO side , resulting in an improved light extraction efficiency .
 Chemical: ZnO
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: ZnO