Sol - Gel Preparation Of Zno: Cd Film And Performance Study

Zinc oxide (ZnO) is a novel wide direct-gap semiconductor with crystal lattice constant of a=0.3250nm and c=0.5206nm. It possess large room temperature band gap of 3.30eV and a high binding energy 60 meV. It have been uesed to fabricate display devices, high frequency filters, emitting diode, lasers and high-speed optical switch due to its high blue transmitting and ultraviolet radiation.It is common for wide band-gap semiconductor to dope minim element to alternate the optoelectronic property. It is one of hotspots by doping Ag, Cu, Li or N to attain P-type ZnO films and doping Mg or Cd to change the optical band-gap of ZnO films.There are many techniques uesd to deposition ZnO thin films, such as sputtering, chemical vapor deposition (CVD), pulse laser depositon (PLD), molecular beam epitaxy (MBE), sol-gel and so on. However, these processes have the disadvantage of the need of vacuum apparatus. The sol-gel mothod not only has voided the disadvantage, but also has the potential for preparation of films of large size and complicated forms on various substrares. Now it was few previous reports involving ZnO:Cd thin films by sol-gel technical.In this dissertation, ZnO:Cd thin films were prepared on the glass, Si(100) and quartz substrates by the sol-gel process using a spinning-techniques in order to study the influence of the process condition on the crystallization, orientation and morphology of the films.Then the films with the optimum properties are obtained by improving the process conditions.The relations between the structure of the ZnO:Cd thin films and resistivity and transmittivity are found.The ZnO:Cd films show a hexagonal wurtzite structure with c-axis orientation as observed by XRD spetrum. With the increase of heat-treating temperature,the intensity of diffraction peak increased and FWHM reduced.When doping Cd, many peals are found in the (002) peal.The better prepartion of ZnO:Cd thin films is from Cd 6at.% to Cd 8at.% under 800℃annealing temperature. It is practicable to reduce its optical bandgap of the thin films by temperate Cd-doped method. Surface resistance showed that the Cd-doped way maked the electric properties of ZnO thin films improve.