Zhuo Xu, Qing-Rong Zheng, Gang Su
By means of first-principles calculations within the density functional
theory, we study the structural and optical properties of codoped ZnO nanowires
and compare them with those of the bulk and film. It is disclosed that the low
negatively charged ground states of nitrogen related defects play a key role in
the optical absorption spectrum tail that narrows the band-gap and enhances the
photoelectrochemical response significantly. A strategy of uncompensated N, P
and Ga codoping in ZnO nanowires is proposed to produce a red-shift of the
optical absorption spectra further than the exclusive N doping and to get a
proper formation energy with a high defect concentration and a suppressed
recombination rate. In this way, the absorption of the visible light can be
improved and the photocurrent can be raised. These observations are consistent
with the existing experiments, which will be helpful to improve the
photoelectrochemical responses for the wide-band-gap semiconductors especially
in water splitting applications.
View original:
http://arxiv.org/abs/1202.5364
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