Ultraviolet Luminescence Of ZnO Nano-crystal Film Under Field Emission Electron Excitation

Nowadays energy conservation and environmental protection have become the twodominant themes of the times, thus raising a new assignment to optoelectronic industry:to develop new luminescent devices that are more efficient, more low-cost andenvironmentally friendly. On the other hand, ultraviolet light source plays vital roles infields such as environmental depollution, organic polymerization, fluorescenceexcitation and semiconductor technology. Moreover, as the excitation source offluorescent power, ultraviolet light source counts for much in achieving white-lightLED. However, environmental pollution problems caused by traditional UV Mercurylamp become more and more serious, calling for studies and researches on new UVlight-emitting devices. As the foundation of new UV light-emitting devices, the wideband-gap semiconductor materials represented by ZnO turn out to be quite noticeable.This project is targeted in developing of high efficiency UV light-emitting devices,aimed at researches on the UV luminescence properties of ZnO under electronexcitation. Main tasks and achievements are as followed.1. Optimum technology parameters are obtained by utilizing RF sputtering andhydrothermal method while ZnO nano-crystal films with uniform and dense distributionare prepared at the same time. The photoluminescence (PL) spectrums of ZnOnano-crystal films prepared under different parameters are collated to analysis luminousmechanism of different emission peaks, which can provide reference and comparison toresearches on luminescence properties of the same sample under electron excitation.2. The author make a further exploration on the preparation technics of carbonnano tube (CNT) by utilizing microwave plasma chemical vapor deposition (MWPCVD)after summing up the available research-achievements. Meanwhile the morphology andemission property of CNT samples are tested soon after being prepared.3. Necessary equipments are designed and processed before experiments in whichthe luminescences of ZnO nano-crystal films under electron excitation are tested. Theresults show that under the excitation of electron beam, the spectrum of ZnOnano-crystal film had two emission peaks in which the yellow or green peak was based on defect luminescence while the ultraviolet peak originated from intrinsic excitons ofZnO. With the increase of electron beam density, the ultraviolet peak grew rapidly. Inaddition, different from usual ZnO film, the ultraviolet peak of ZnO nano-crystal filmspectrum red-shifted to violet band.4. Optimization plans are put forward after analyzing mechanism of red-shift ofspectrum while structure of samples and the testing process are redesigned at the sametime. The results are satisfied: the extent of red-shift is reduced obviously and defectluminescence is restrained more efficiently. Furthermore, the luminescent intensity ofZnO nano-crystal film is increased by44.1%, showing a significant improvement ofelectro-optical conversion efficiency.