The Study And Fabrication Of Luminescence And Ultraviolet Photodetector Device Based On ZnO Microwire

Ultraviolet photoelectric device have a widely application in green lighting, optical communication and ultraviolet detection. II-VI group semiconductor zinc oxide(Zn O) is a wide direct band semiconductor with a band gap of 3.37 e V and an exciton binding energy as large as 60 me V, which could act as a promising candidate material for ultraviolet laser diode. And Zn O is also an abundant, inexpensive and experimental material. Zn O can be easy to synthesize many different kinds of nanostructures, and for the good crystal quality and quantum effect of these nanostructures, they have more important potential in the application of luminescence and ultraviolet detection device. Zn O microstructures not only possess high crystal quality, but also have a more appropriate size of operating and fabricating device than nanosturctures. Meanwhile, Zn O microstructures can be act as a micro laser cavity. In this work, we focus on the controllable growth of the Zn O microstructure and the fabrication of its photoelectric device, and made the following innovative research results:1. We synthesize the Zn O microwires with the quadrate cross section by a chemical vapor deposition method, which size can be controlled by the growth temperature. Ag nanoparticles were used to enhance the photoluminescence of Zn O microwires. For the optical restriction of the F-P cavity mode of the microwires, the photoluminescence can be a 102 times enhanced in ultraviolet wave band after Ag nanoparticle sputtering on the Zn O microwires.2. We fabricate an electroluminescence device with green emission centered on 500 nm based on the microwires. Once the Au nanoparticles are sputtered on the surfaces of Zn O microwires, the electroluminescence of the Zn O microwires will shift from green emission to red emission centered on 600 nm, and this is due to that there is an energy transfer process from the surface defects of Zn O microwires to the Au nanoparticles under the electric driven. The distribution of Au nanoparticles on the microwires can be controlled under a template, and dual emissions have been observed by sputtering Au nanoparticles on the Zn O microwires periodically.3. We synthesize Zn O-Ga2O3 core-shell microwires with high crystal quality by a simply one-step chemical vapor deposition methods, in which the Zn O crystal lattice could abruptly switch to the Ga2O3 crystal lattice within 6-8 atomic layers without noticeable structure defects at the interface between two materials. High-performanced solar-blind(200-280 nm) avalanche photodetectors(APDs) were fabricated based on the Zn O-Ga2O3 core-shell microwires. The responsivity can reach up to 1.3×103 A/W under-6 V. Besides, the corresponding detectivity was as high as 9.91×1014 cm·Hz1/2/W. The device also had a fast response with the rise time shorter than 20 μs. The quality of the detectors can be comparable or even higher than the commercial Si APD in solar-blind waveband. It is found that the external quantum efficiency can be as high as 2.53×106 % under-10 V bias. A positive temperature coefficient confirmed that the high internal gain of our photodiode was originated from the avalanche multiplication.