Growing ZnO Nanoparticles On Si Substrates By Implantation And The Effect To Growth Behavior Of ZnO Film

ZnO is a direct band-gap semiconductor(Eg=3.3eV at RT) with a high exciton binding energy of about 60meV.The feasibility of using excitionic lasers of ZnO at RT has been demonstrated.Besides,ZnO thin films can be prepared at temperature lowerthan 600℃,its growth temperature is lower than GaN,SiC and otherâ…¡-â…£semiconductor materials.Owing to these properties,ZnO can be used asroom temperature short wavelength ophotoelectron material.It has been investigated extensively because of its interesting electrical,optical and piezoelectric properties making suitable for many applications such as light emitting diodes, photodetectors,electroluminescence,transparent conductive film,surface acoustic waves device and so on.The renewed interest of ZnO film is fueled since room temoerature lasing was reported by Tang et al.In this thesis,implantation and the reactive radio-frequency(RF) magnetron sputtering method are used to deposite ZnO nanoparticles and ZnO films.This work is focus on the growth behavior and the optical properties.The results are summarized as follow:1.Si(001) chips are implanted by Zn ions of 40 keV with different ion dosages and are annealed in air at different temperatures.It is found that the as-implanted Zn atoms aggregate into clusters scattering about 35 nm beneath the surface of the chips.During the annealing process,Zn atoms are found to migrate toward the surface of the chips and aggregate into nanoparticles at the interface between the amorphous SiO₂ layer and polycrystal Si layer. Annealing temperature is found to be the crucial factor controlling the formation of ZnO nanoparticles.ZnO nanoparticles begin to appear at about 400℃and the diffraction intensity of ZnO becomes strong while the diffraction intensity of metallic Zn weakens with increasing the annealing temperature.At the annealing temperature of 800℃,(Zn)₂SiO₄ phase is observed due to the reaction between ZnO and SiO₂ or Si.2.ZnO thin films were deposited on Si implanted by Zn ions of different doses.It is found that all the films show highly c-axis textured structure and the surface morphology is strongly dose-dependent.The AFM show that the films have an increase in size with the implanted dose, and islands are inclined to together as implanted a mass of Zn.Plan-view TEM micrographs and corresponding SAD patterns show that the films have a highly c-axis orientation. Implantation makes SAD patterns of ZnO film being a close diffractive ring and possessing great symmetry.Besides the highly c-axis orientation,ZnO has fixed orientation relationship in the direction of paralleling the surface.3.Using reactive radio-frequency magnetron sputtering,ZnO films were deposited on Si (001) substrates with plused negative bias.The atomic force microscopy was used to study the morphological evolution of ZnO films.The nucleation and growth behavior of the films are quantitatively characterized with the dynamic scaling theory.It is found that the island density of ZnO films increases and the grain size decreases with increase of the deposition time.Compared with the film depositions without bias,the stage of low-rate nucleation disappears due to the application of plused negative bias.The growth exponents of the native-defect nucleation and the ion-bombardment defect nucleation are determined to be 0.45±0.03 and 0.22±0.04,respectively;With increasing the voltage of plused negative bias,the island sizes and the roughness increase and the preferred orientation of the films is found to change.