Electronic Structure Study of N, O Related Defects in GaP for Photoelectrochemical Applications

It is known that the stability of GaP as a photocatalyst in electrolytes can be enhanced by nitrogen doping, GaP:N. However, both GaP (indirect gap) and GaP:N (direct gap) have poor optical absorption properties across their fundamental band gap. To enhance optical absorption as well as the photocurrent, we have examined by density functional theory the favorability of oxygen and hydrogen impurities in conjunction with N doping in bulk GaP. It has been found here that O-related defects are more favorable, whereas H with N substitution is not very favorable. These O-N related defects create a global effect in the GaP lattice by both volume and band gap reduction. Enhancement of optical absorption was also found due to these types of complex doping.