20409
Theoretical modeling of the electronic structures indicates that the reduction of the effective mass at the valence band maximum ( VBM ) with decreasing sheet thickness enhances the carrier mobility of the GaS nanosheets , contributing to the high photocurrents .
 Chemical: GaS
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: GaS 
Answer:
 Chemical: GaS