Chemical Vapor Deposition Of N Doped Zno Thin Films And Performance

Zinc oxide is a wide-band-gap semiconductor material (3.37eV) with high exciton binding energy (60meV) which is much higher than other wide-band-gap semiconductor material. It has been considered as promising material applying in short-wave optoelectronic device, such as ultraviolet light emitting diodes (LEDs) and laser diodes (LDs). To realize these optoelectronic wide application, it was very imperative to fabricate both n-type and p-type ZnO films. Intrinsic ZnO films are natural n-type conduction, and it is available to get n-type ZnO films with good quality through doping. However it is hard to obtain p-type ZnO films.In the thesis, ZnO films with p-type doping were prepared by CVD using Zn₄(OH)₂(O₂CCH₃)₆·2H₂O as solid source and NH₃ and ZnNO₃ as doping material respectively. The main results are as follows:1. NH₃ was choiced as doping material to prepare N-doped ZnO films, the influence of the source temperatures and NH₃ flow rate were studied. X-ray diffraction (XRD), Hall effect and photoluminescence (PL) were employed to investigate the structural, electrical and optical properties of the films. Results showed the growth of the films was influenced by source temperature. The higher crystal quality films were obtaind at source temperature of 200℃, with higher ratio of near-band-edge emission intensity to emission related to deep level defects in PL spectra. The NH₃ flow rate didn't have obvious influence on the preferential orientation of the films, the films with difference flow rate were n-type conduction with large resistivity. the XPS study showed the amount of the N elements doped in films was less to compensate the n-type conduction.2. ZnNO₃ was choiced as doping source of N-doped ZnO thin films, the influence of the substrate temperatures was studied. XRD, Hall effect and PL spectra were employed to investigate the structural, electrical and optical properties of the films. The results showed that the ZnO thin films exhibited (002) preferential orientation as the substrate temperatures below 500℃, but exhibited mixed orientations when the substrate temperature was 500℃, when the substrate temperatures were above 500℃, the film exhibited (002) preferential orientation again. Hall effect mesuarment results showed that the thin films were p-type conduction as the substrate temperature below 600℃, and the films transited from p-type to n-type conduction as 600℃. The study on the effect of annealing temperature showed the crystal quality was improved with suitable annealing temperature, but the quality became bad with too high annealing temperature; the annealing temperature also influenced the intensity of near-band-edge emission intensity and emission intensity related to deep level defects.