Study On Preparation Of One-dimensional ZnO Nanorod Array And Its Light Emitting Device

As a typical third-generation semiconductor,ZnO has been regarded as a promising candidate for short-wavelength semiconductor light-emitting devices due to its band gap of 3.37e V and a room-temperature exciton binding energy of 60 me V.However,due to the difficulty of realizing the p-ZnO with low resistance and stability,the practical applications of ZnO have been seriously hindered.Therefore,n-ZnO/p-Ga N heterojunction light-emitting diode（LED）devices have been widely studied to solve this problem.In order to improve the luminous efficiency of heterojunction devices,materials with good crystal quality are usually adopt as the active layer.One-dimensional ZnO nanorods array（ZnO NRA）has attracted people’s attention due to its excellent photoelectric conductivity.With the development of research,new problems have arisen.Due to the large specific surface area of nanostructures,device performance is difficult to control,especially the luminescence of ZnO NRA becomes more complex.In order to explore the luminescence characteristics of one-dimensional ZnO NRA and its devices,in this paper,we investigated the luminescence mechanism of ZnO NRA,device structure of ZnO NRA and the influence of modification of Ag nanoparticles（AgNPs）on enhanced luminescence,etc.The main contents are as follows:（1）ZnO NRA was prepared by solution method,and the effects of substrate,seed layer type,seed layer thickness and other factors on the growth of ZnO NRA were systematically studied,and a relatively mature preparation process of ZnO NRA was then obtained.The ZnO NRA with high density and good vertical orientation was successfully prepared by pulsed laser deposition（PLD）on c-Al₂O₃ and p-Ga N substrates to prepare Mg ZnO and ZnO/MgO double layer films as seed layers.In c-Al₂O₃ and p-Ga N substrate,Mg ZnO prepared by pulsed laser deposition（PLD）method and ZnO/MgO style double film as the seed layer,the successful preparation of the high density and good vertical orientation of the ZnO NRA through variable photoluminescence（PL）spectra of the ZnO is studied in the NRA glow causes,the near band-edge emission（NBE）of ZnO NRA attributed to free exciton related compound,which is in the defect emission（DE）of visible light are regarded to be associated with different valence state of oxygen vacancies（V_O）related flaws.These V_O of different valence states can be converted to each other with the change of ambient temperature,which provides a rich experimental basis for the study of luminescence characteristics of ZnO NRA.The relationship between the morphology of ZnO NRA and its photoluminescence（PL）spectrum was also analyzed,and it was found that the relative emission intensity of NBE and DE of ZnO NRA could be adjusted by controlling the morphology,which provided a new way to regulate the performance of luminescence devices.（2）According to the energy band engineering,ZnO/MgO double-layer structure was selected as the seed layer and the limiting layer,and ZnO NRA/ZnO/MgO/p-Ga N heterojunction luminescent device was designed.In was selected as the electrode of ZnO NRA and Au/Ni as the electrode of p-Ga N.The preparation technology of the device electrode was studied and good ohmic contact was obtained.Electroluminescence based on ZnO NRA defect was obtained by using dc excited ZnO NRA/ZnO/MgO/p-Ga N heterojunction device at room temperature under positive forward bias,and the chroma of the device can also be adjusted with the variation of bias voltage.The luminescence mechanism of the device was analyzed systematically,and it is believed that the ZnO NRA defect luminescence originates from V_Orelated compound of different valence states under the action of electric field.Due to the effect of oxygen adsorption on the surface of ZnO nanorods,V_O on the surface and in the body of ZnO nanorods presents different valence states,and the charged state of V_O changes with the variation of bias pressure and environmental temperature,leading to the shift of luminescence peak.（3）The effects of AgNPs modification on the luminescence performance of ZnO NRA were studied.Firstly,Ag films with different thickness were evaporated by thermal evaporation,and AgNPs of different particle sizes could be obtained during heat treatment.It is found that AgNPs dipole resonance peak is strictly controlled by its particle size and particle size distribution,and quadrupole resonance is more likely to occur in AgNPs particle with larger size.AgNPs with different particle sizes were prepared on ZnO NRA by thermal evaporation.The NBE enhancement effect of ZnO NRA was realized by using the quadrupole resonance of AgNPs.The use of AgNPs dipole resonance peak can generate DE resonance enhancement of ZnO NRA,and the amplitude of enhancement is related to the matching degree of peak position between them.AgNPs solution was successfully prepared by microwave oven heating method,and the influence of reaction solution ratio,reaction time and heating power on the absorption spectrum of AgNPs solution was studied.AgNPs with high stability and good dispersion was successfully prepared by laser induction,and the particle size was uniformly distributed at about20 nm.The AgNPs spin coating process of ZnO NRA was investigated,and the NBE luminescence enhancement of ZnO NRA was obtained by the AgNPs modification prepared by biosynthesis.