Preparation And Optical Properties Of Nanocrystalline Zno Films

Zinc Oxide (ZnO) is a wide band-gap semiconductor (3.37eV at room temperature) with the high exciton binding energy of 60 meV. Since the ultraviolet (UV) lasing from ZnO was realized in 1997, the study on ZnO has attracted a great deal of attention because of the intense commercial interest in developing practical short-wavelength semiconductor diode lasers (SDLs) for the huge market needs.We introduced allsidedly preparation, properties and foreground in application about ZnO thin films; We introduced emphatically the principle and method about pulsed laser deposition (PLD), which was adopted in our work. ZnO thin films were prepared respectively on Si and silica glass substrates with method of pulsed laser deposition, at different oxygen pressure and different pulsed laser energy. The X-ray diffraction (XRD) pattern of the samples showed only one sharp diffraction peak for ZnO (002), which indicated that the thin film was highly c-axis oriented. And comparative studies of AFM of the samples revealed that the thin films we got presented a smooth surface. The transmission spectra were researched, and we found that transmittance was only 3.6% in UV area. And the photoluminescence spectra showed that there are not only two emitting peaks at around 380nm and 520nm but also an infrared emitting peak, which was found for the fist time. In order to enucleate green light emission mechanism of ZnO thin films, we studied it with the method— deep level transient state analysis method. The method is different from the other deep level transient state analysis method that experimental equipment is complicated. Experimental equipment is ordinary and accurate. In our experiment we utilized the characters of p type Si substrate and ZnO that ZnO is crude n type ZnO material. Onthe grounds of the variation of \n(en/T2) with 1000/Jof defect level of n typeZnO thin films, we got the defect level------1.62 eV from conduction band, whichwas anastomosing with defect level of ZnO in doctoral dissertation of Sun Yu-ming. This conclusion supported the theory that green light emission mechanism of ZnO thin films attributed to electron transition from conduction band to oxygen vacancy defect level.Not only is the present work a solid base for further research on ZnO thin films nano-particles, but also an active endeavor in the application process.