3.3.1 Band Structure
We measured the band structures of pure SrTiO3 as well
as effect for Ag atom doping upon the electronic properties of
SrTiO3. The band structure of both pure and doped
SrTiO3 are shown in Fig 2 (a) & (b), respectively. We
can see that maximum of valance band (VB) present at point R and the
minima of conduction band (CB) present at point G, which confirms the
indirect band gap of pure SrTiO3. Taking such two
approximation points into consideration, the calculated bandgap of pure
SrTiO3 is 1.91eV and Ag-doped SrTiO3 is
2.18 eV. This indirect band gap findings are nearly matched with
previous study. As we can see that in the case of pure
SrTiO3, the value of direct band gap is lesser than the
value which is obtained by experiment which is 3.2 eV [22]. From Fig
2(b), both minima of conduction band and the maxima of the valence band
present at same point āGā throughout the observed results of Ag-doped
SrTiO3 and after doping the indirect band gap was
converted to direct band gap. The graph reveals that the VB of
Ag-SrTiO3, especially at point G, is transferred up than
that of pure SrTiO3 [15,16].