A STUDY ON STRUCTURAL AND OPTOELECTRONIC PROPERTIES OF ZnO FILM PREPARED BY PULSED LASER DEPOSITION ON Si(111) SUBSTRATES

Zinc oxide (ZnO) thin films grown on Si(111) substrates by pulsed laser deposition at O2 ambient pressure of 1.3 Pa at different deposition temperatures have been studied. ZnO thin films underwent annealing treatment after deposition. The structural and optoelectronic properties of deposited and annealed thin films have been characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), infrared absorption (IR) spectra, four-probe measurements and photoluminescence (PL) spectra. The XRD observation shows that the best crystalline quality of ZnO thin films with hexagonal structure are those grown at a temperature of 400°C and annealed at a temperature of 600°C, respectively. AFM results show that the surface roughness of the ZnO films can be decreased with increasing annealing temperature up to 600°C and then increased by further increasing the annealing temperature. The intense absorption peak sited at 417.54 cm-1 has been observed by IR spectra for ZnO film grown at 400°C and annealed at 600°C, and the property of absorption is improved by post-annealing. ZnO film grown at 400°C with a resistivity of 12.3 Ω·cm shows the best n-type semiconductor property. The PL spectra show the dominant increase in UV emission by annealing. It is concluded that the best post-annealing temperature is about 600°C.