5874
A protective layer of Si oxide is found to exist on the outer wall of the SiNWs and to play the key role of etch mask during the release - etching by alkali hydroxides .
 Chemical: Si; Chemical: oxide; Chemical: alkali hydroxides
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: Si; Chemical: oxide; Chemical: alkali hydroxides