Preparation And Characterization Of ZnO Thin Films And P Doped ZnO Thin Films

ZnO is a wide direct band gap semiconductor (Eg=3.37eV at RT) with an exciton binding energy of 60meV, and a hexagonal wurtzite structure. As a new generation of wide-band semiconductor material, ZnO has been applied widely, such as the short wavelength ophotoelectron devices, transparent conductors, surface acoustic wave resonator, piezoelectric nanogenerator, etc.In this paper, ZnO films and ZnO:P films were deposited at various conditions using pulsed laser deposition (PLD). Scanning electron microscopy, atom force microscopy, x-ray diffraction, electron probe micro-analyzer and photoluminescence are used to study the surface morphology, microstructure, compositions, and the optical properties of the ZnO films and ZnO:P films. The results are summarized as follow:â… . By using pulsed laser deposition method, ZnO films with high c-axis orientation were deposited on (100) silicon substrates at different oxygen pressures. It is found that the surface roughness of the films increases with the oxygen pressure. In the oxygen pressure ranging from 0.2 to 5.0Pa, the crystalinity of the films is improved with the increase of oxygen pressure. All the films show near-band emission at 3.29eV. The low-temperature PL spectra reveal that the 3.314eV PL peak is attributed to be from the transition of (D0, h). The corresponding energy level of the shallow donors is estimated to be 124 meV below the conduction band minimum.â…¡. By using pulsed laser deposition, ZnO films with the c-axis texture were prepared on Si (100) substrates at different laser energy. It is found that all the ZnO films have the similar surface morphology. The surface roughness of the films is related to the laser energy. It is found that the films grown at about 186 mJ has a high crystalinity.â…¢. By using pulsed laser deposition method, ZnO:P films with high c-axis orientation were deposited on c-plane sapphire substrates at different oxygen pressures. It is found that high oxygen pressure is helpful for the phosphorus doping. SEM shows P-rich particles aggregate on the surface of films. The P-doping results in the variation of the film crystalinity.