Abstract:
We characterize the physically produced Li-doped ZnO having concentration of lithium 2,4,6
and 8% and Li co-doped (Zn, Co)O in which cobalt concentration is fixed at 4% thin films
fabricated by pulsed laser deposition technique. The effect of lithium doping in pure ZnO and in
ZC4 is investigated. Electrical and optical properties of samples were studied by Hall
Measurements which include measurement of sheet resistance, resistivity, conductivity, mobility
and carrier concentration. Spectroscopic ellipsometry was done for optical studies, by modelling
the ellipsometry spectra we get reflection and extinction coefficient, refractive index, dielectric
constants, amplitude and phase ratio along with thickness. Zinc oxide has a hexagonal wurtzite
crystal structure, optical bandgap is calculated by Beer Lambert Law it is observed that by
increasing doping concentration optical bandgap increases. From the results of Hall measurements,
it is observed that change in the conduction type from n- to p-type is due to Li doping. Resistivity
decreases sharply at 4% lithium co-doping due to which conductivity is increased. From
temperature independent ellipsometry results it is concluded that values of extinction coefficient
and refractive index and started decreasing as wavelength increase, sharp peaks were observed in
visible region. The crystalline structure of ZnO can be improved by lithium doping and can be
used in the Organic Light Emitting Diodes. Li doping enhanced device performance
and luminescence and can be used for fabrication of OLEDs. This material could be used in light
emitting diodes in nanoscale optoelectronic devices.
