ZnO Nanostructure Based UV Optoelectronic Devices

UV optoelectronic devices have important applications in environmentallyfriendly lighting, optical communication, optical information storage and so on.Direct band-gap semiconductor zinc oxide (ZnO) of group II-VI has the band-gap of3.37eV and a exciton binding energy of60meV, which is much larger than thethermal energy at room temperature (26meV). So ZnO is a promising candidatematerial for ultraviolet light emitting diodes and lasing diodes at room temperature.Meanwhile, ZnO raw material is abundant, non-toxic. Therefore, ZnO is animportant material for semiconductor untraviolet laser, which has been the new hotspot in the short-wavelength semiconductor laser materials and device researchfollowing the GaN material. Zinc oxide has variety of nanostructures, due toquantum effects, ZnO nanostructures with different morphologies exhibit differentand unique characteristics in their own, which will lead to potential applications. Inthis article, we designed and fabricated ZnO nanostructures with differentmorphologies, on the basis of the features the ZnO nanostructures presented, wehave fabricated the optoelectronic devices with superior performances and novelfunctions:1. A ZnO micro-cavity structure have been fabricated on the p-type GaNsubstrate through photolithography process and hydrothermal growth method, on the basis of the ZnO micro-cavity structure a UV light emitting diode with a lowerthreshold, a higher brightness and a luminescence peak at395nm has been made.2. A ZnO nanocrystalline film has been prepared directly on the ITO electrodeby a novel annealing method, then a ZnO nano-crystal/p-GaN heterojunction lightemitting diode was got. The emitting peak of the device blue-shifted to383nm, thefull width at half maximum of the peak was narrowed to13nm and thecorresponding threshold current was0.62mA.3. Artificial leaf structures have been fabricated by the self-assembly of ZnOnanoparticles. A hydrothermal method was used to synthesize the nanoparticles. Theself-assembly patterns showed a broad absorption band and high resistance. Ahigh-performance ultraviolet detector was fabricated on the artificial leaf structures,which showed that the current under the irradiation of a UV lamp was about104timesgreater than in the dark.4. A CdSe/ZnS quantum dots based photodetector have been fabricated througha simple approach. The photodetector presents broad spectral detecting ability, andthe responsivity of the device could reach up to400mA/W. Under different incidentwavelengths, the photocurrent changes according to the spectral response curve ofthe device, which could realize the wavelength detection of incident light.5.2D photonic crystals of ZnO have been successfully fabricated by a simple PSmicrosphere-assisted templating technique. The band gaps of the array structurewere investigated by the optical transmission spectra. According to Mie’s scatteringtheory, we have accurately deduced the band structure and changing regularity thatfit the experimental results well. It is proved that the2D array structures couldchange and enhance the performance of optoelectronic devices based onsemiconductor.