Since
SrTiO3 is energetic compound of optical electronic
devices, we examine result Ag doping with SrTiO3lattice. Properties of optical such as reflectivity, absorption,
refractive index (n), refractive index (k), loss function, real part and
imaginary part of dielectric function and real part of conductivity
describe how light interact with matter. Firstly, we calculated these
optical properties of pure SrTiO3 compound and after
this we compare the optical properties with Ag doped SrTiO3 compound
shown in Fig 4. We analysis that these optical properties are frequency
dependent and interconnected.
Ag doped SrTiO3, all points where the absorption is
lowest, the reflection Fig 4(b) is found to be maximum. Here we analyze
that the presence of doping slightly changes the absorption spectra.
As shown in Fig 4(e & f) the dielectric function is divided into two
parts: First is real part and second is imaginary part. The real part of
dielectric function (DF) represents polarization, while the imaginary
part describes energy dissipation within the framework. In the case of a
pure SrTiO3, the imaginary component of DF is 0 at 0
electron Volt. It illustrates that energy dissipation (absorption) is
zero inside the SrTiO3. If we compare this value with
the Ag-doped SrTiO3 we observe that energy dissipation
is present at 0 electron Volt. The imaginary part of DF shows four
highest peaks which observed at 4.12, 7.28, 23.02 and 36.33 electron
Volt of pure SrTiO3, which relates the 4 absorption
peaks depicted in Fig 4(a). Ag-doped SrTiO3 shows
notable peak at 8.69eV and absorption peak at 23.80 electron Volt is
slightly decreases for doped SrTiO3. It can be observed
Ag-doped SrTiO3 system indicates do not a change in
absorption peaks from high energy to low energy, but also a transfer in
absorption peaks away from high energy. The energy area in which
electrons do not generally bound to their lattice positions and conduct
plasma oscillations upon light exposure defined as the maximum loss
function. In comparison to the pure SrTiO3, we analyze
that the Ag-doped SrTiO3 a high peak of plasma
oscillation has shifted to smaller energies. Fig 4(d) shows that the
energy loss function of doped SrTiO3 reaches its maximum
value as compare to pure system of the dielectric function. The both
parts of refractive index (n & k), which based on energy (frequency),
make complex refractive index shown in Fig 4(g & h). The doped system’s
refractive index (n) is estimated to be 3.23eV, which is significantly
higher than the pure system’s (2.50 eV). After Ag addition, the
refractive index (n) of semiconducting SrTiO3 shifts to
higher values, confirming the transition of semiconducting
SrTiO3 to metallic material. The lowest absorption
energy is correlated with highest refractive index value at zero photon
energy. The refractive index decreases as absorption increases, as seen
in Fig 4(g). The annihilation of energy in the system defined be with
extinction coefficient, which correlated by the absorption spectrum. At
photon energy is 1.3eV, the extinction coefficient of pure
SrTiO3 is zero, which is the same as its indirect band
gap and until 1.3eV, there is no extinction of energy inside the
substance. So, that it has zero absorption. The refractive index (n)
rises in parallel by absorption. The refractive index (k) of Ag-doped
SrTiO3 has transferred to a lower energy, with sharp
peaks occurring at about 4.40eV, 8.50eV, 19.65 eV, 23.68eV and 36.41eV
[19-21].