Homogeneous ZnO P-n Junction For Blue Light-emitting Diode Applications

Zinc oxide(ZnO)semiconductors have great application prospects in the field of short-wavelength optoelectronic devices such as blue-violet light and ultraviolet light due to their large forbidden band width(3.37 e V)and high exciton binding energy,and are expected to become the next generation of solid-state lighting.Core light source material.However,the high hole concentration,the stability of the shallow donor level,the p-type doping and the high concentration defect state introduced by doping restrict the application and development of ZnO-based blue light-emitting devices.The high-quality epitaxially grown ZnO nanowires have the advantages of low defect concentration,morphology and doping controllability,and are expected to solve the problems of p-type doping and poor luminescent properties of ZnO-based thin film materials.In this paper,Sb-doped ZnO nanowire arrays were prepared by chemical vapor deposition(CVD).The relationship between nanowire diameter and its conductivity was investigated.The high quality of n-ZnO single crystal substrate/p-ZnO nanowire array structure was constructed.The blue LED device is analyzed by its electron-hole composite luminescence mechanism,and the corresponding energy band structure model is established.The research content of this paper can be concluded into three as following:1,Sb-doped ZnO nanowires with different diameters were deposited on sapphire(c-Al2O3)by chemical vapor deposition.The effects of nanowire diameter on their crystallinity,defect concentration and conductivity were investigated.The experimental results show that as the diameter of the nanowire increases,the crystallinity of the nanowire becomes worse,the defect concentration increases,and the conductivity of the nanowire changes from p-type to n-type.The nanowire-doped Sb is discussed in detail to realize the p-type transition.Mechanism and the reason why the nanowire diameter affects its conductivity.2,Successful preparation of n-ZnO single wafer/p-ZnO nanowire array homojunction blue LEDs was achieved.The characteristic curve of a single Sb-doped ZnO nanowire FET indicates that the Sb-doped ZnO nanowire array is p-type conductive;at 4 V-10 V,the blue light-emitting diode achieves stable blue light emission;the luminescent center is at 425 nm,and the LED color temperature is(0.33,0.33),the analysis results show that the electrons in the n-ZnO single wafer and the holes in the p-ZnO nanowire array recombine at the interface at the interface,realizing the effective adjustment of the energy band,making the ZnO intrinsic luminescence peak Red shift to the blue light luminescence peak to achieve blue light emission.3,In this paper,the gradient doping of ZnO nanowire array was prepared by heat evaporation and high temperature annealing.By controlling the thickness of evaporation deposition and annealing time,the axial and radial homogenous and gradient doping of nanowire arrays can be realized.The gradient doping of the nanowire can make the doped elements form a gradient distribution inside the nanowire,improve the carrier transport rate,and facilitate the combination of electrons and holes in the doped area.We successfully realized the p-type doping of zinc oxide nanowires on n-type ZnO substrates by chemical vapor deposition,and designed the LED structure of n-ZnO /p-ZnO nanowire arrays,successfully achieving homogeneity.The blue light emission of the junction LED will lay an important theoretical and experimental basis for the key material preparation technology,electrical transport and electroluminescence mechanism of ZnO-based blue LED devices.