Oxygen-Impurity-Induced Direct Indirect Band Gap In Perovskite Srtao2n
JOURNAL OF PHYSICAL CHEMISTRY C(2017)
摘要
Oxynitride semiconductors are considered to be promising candidates for solar water splitting. In this work, we show that oxygen-rich SrTaO2N has a band gap with direct-indirect character through twin valence-band maximums (VBMs), resulting in good photoelectronic responses. Compared with the direct band gap of ideal SrTaO2N, the additional indirect VBM of the oxygen-rich solid solution was found to be due to strontium-oxygen hybridization, using orbital projections based on hybrid/GW density functional theory (DFT). This twin-VBM character was validated by strontium Kedge absorption through extended X-ray absorption fine structure (EXAFS) analysis. The twin-VBM character of the band structure can enhance the photoelectronic response and hole transport. Our findings provide a viable strategy for enhancing the solar water splitting performance of oxynitrides.
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