Preparation And Properties Of Transparent And Conductive ZnO: Ga Film By DC Magnetron Reactive Sputtering

Zinc oxide (ZnO) is a novel II-VI compound semiconductor with a hexagonal wurtzite structure. It grows usually along the [0001] orientation due to its lower surface free energy for the (002) plane. ZnO is a unique material that exhibits optoelectronic, piezoelectric, and ferromagnetic properties, as well as its versatile nanostructures. In particular, it is a potential candidate for applications in short-wavelength optoelectronic devices, including light emitting diodes (LEDs) and laser diodes (LDs), due to its direct wide-band gap (3.37 eV) and high exciton binding energy (60 meV, cf. 25 meV for GaN), which will favor efficient excitonic emission at room temperature. In addition, good quality n-type ZnO films have been prepared by doped IIIA elements (Al, In, Ga). The resistivity of the film can be down to 10~-4Ωcm;The transmittance of the film can be more than 90% in the visible region. All the films were of good crystal quality with high (002) orientation and closed packed columnar grains, which can be used for contact electrode in LEDs.This thesis is that preparing Gallium doped zinc oxide (ZnO:Ga) films on glass substrates by DC magnetron reactive sputtering and using various testing technique to analyze the performance of the film.The main content of this thesis is listed as follows:1. The obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the [0001] crystallographic direction in the ZnO grains by XRD testing and the Ga atom in the film occupies the Zn position or distributes in the boundary of the crystal2. Good quality, compact surface and integrated structure have been observed by SEM. Hall testing shows that the resistivity of the film is lower than other ZnO films and the carrier concentration is much higher. The contact between the film and electrode is ohm contact. The transmittance of the film can be more than 90% in the visible region.3. Studying the dependence of the performance of the film on the experimentalparameters, we find out the optimal value of various experimental parameters: the flux of O2 and Ar are 5sccm and 40sccm;the substrate temperature is 275 °C;the sputtering pressure is 1.5Pa;the sputtering power is 130W;the target-substrate distance is 6cm.4. The lowest resistivity of the film is 2.32 X 10"3Qcm, the carrier concentration is 1.27X1020cm"3o...