GROWTH AND CHARACTERIZATION OF OXIDE MATERIAL FOR NOVEL APPLICATIONS

Abstract

Recently, the oxide semiconductor is very useful for electronic and microelectronic devices. ZnO is most popular oxide semiconductor for making electronic devices. ZnO is a wide band gap semiconductor with the value 3.37 eV. It has large exciton binding energy of 60 meV. It has various applications such as transparent conducting films for solar cells, surface acoustic wave (SAW) devices and opto-electronic devices. Its band structure and optical property is very similar to GaN. It is a good material for the fabrication of optical devices such as light emitting diode (LED) and laser diode (LD). In the present work zinc oxide (ZnO) thin films have been prepared by the spray pyrolysis method on glass substrate. Different thickness of the films has been prepared by different volume of precursor solution such as 25 ml, 50 ml, 75 ml and 100 ml. The temperature of the substrate is kept constant at 400°C. X-ray diffraction results shows hexagonal wurtzite structure with (002) orientation and its crystallinity increases with increase in substrate temperature (T). The surface morphology changes continuously with change in substrate temperature (T). The grain size and roughness increases with increasing substrate temperature (T). UV-Vis-NIR absorption spectroscopy showed that the band gap increases when substrate temperature increase. The films of Al-doped ZnO have also been prepared by the spray pyrolysis technique glass substrate. The temperature of the substrate is kept at 500°C. The films have different doping concentration such as 3%, 5%,7% and 10%. X-ray diffraction analysis shows that the crystallite of both undoped and Al-doped films are oriented along the c-axis (002) direction.