Study On The Photoelectric Properties Of Al And P Doped ZnO

ZnO is a direct band-gap semiconductor,which means that its lowest CBM value is in the same position as the highest VBM value,so that the energy consumption of electron transition is minimal.Exciton binding energy up to 60Me V,excellent chemical and thermal stability,and low raw materials are considered to be the most promising materials after gallium nitride for the preparation of LED,transparent electrodes,light-emitting devices and other optoelectronic devices.Due to the asymmetric doping problem of ZnO itself,the breakthrough of ZnO in photoelectric application is not obvious.The main reason is that with the natural growth of n-type conductive ZnO,the existence of donor defects such as oxygen vacancy(V_O),zinc gap(Zn_i)and the incorporation of H atoms in the air will strengthen n-type conductive.However,n-type ZnO can only fill part of the demand in the optoelectronic field,and the preparation of excellent p-type conductive ZnO films with high repeatability and stable performance is the key factor to break the bottleneck.The software used in this paper is Material Studio,which is specially designed for Material analysis.Some preconditions,such as K value,truncation energy,energy convergence precision and crystal stress convergence precision,are obtained by software.Then,BP neural network optimized based on ADAM algorithm was used to train and predict the formation energy of the doped systems.Then,CASTEP modeling was used to analyze the photoelectric characteristics of the systems that were easy to form,to study their specific properties,and to find out the P-type transparent conductive oxide film system with excellent performance and reproducible,so as to facilitate the progress of subsequent experiments.There have been extensive studies on the preparation of N-type TCO films by Al doped ZnO as donor doping,so this paper did not explore the single doping system of Al.The following are the main research contents of this paper.The algorithm is used to predict the easy formation system of p-single doped ZnO,analysis known P single doped ZnO system band gap increases slightly,into n type conductive,the defects of this system can form the lowest,architecture form;The presence of V_znreduces the band gap of the system.With the increase of the concentration of V_zn,the Fermi level enters the valence band,and the system becomes p-type conductive.The reflectivity,absorption and light transmittance are better than the intrinsic and P_znsystems,and the electrical conductivity and formation energy are better than the P_zn-1V_znsystem.For Al,P co-doped ZnO system,Al_znP_znsystem,Al_zn2P_Oand Al_zn2P_znsystem are established.The band and density of states diagrams show that the band gap of Al_znP_znsystem and Al_zn2P_znsystem relative to the intrinsic system increases,and the conduction type changes to N-type conductivity.However,by comparing the optical diagrams,it is found that the two doping systems of P replacing Zn have improved relative to the intrinsic ZnO,especially the improvement of Al_znP_znsystem is the best,which is suitable for the subsequent preparation of N-type thin films.When 1 Al and 1 P are doped with ZnO,P atom can replace Zn atom.However,there are not many papers to prove whether O atom is still replaced when V_znappears.Therefore,various formation energies of the co-doped system with P replacing Zn and O in the presence of V_znare predicted one after another,and then the photoelectric properties of the system easily formed are analyzed.The analysis of energy band and conductivity shows that Al_znP_zn-2V_znsystem is P-type conductive,and the electrical conductivity is the best.Al_zn2P_zn-2V_znsystem has the best optical properties,but this system is N-type conductive,and the band gap is much larger than the intrinsic band gap,followed by p-type conductive Al_znP_zn-2V_znsystem.In general,Al_znP_zn-2V_znsystem is the most suitable for the preparation of high-performance and stable p-type conductive oxide films.For the co-doped system with P replacing O existing in V_Zn,it is predicted that three kinds of systems can be formed easily,and the band gap values of the three systems decrease relative to the intrinsic ZnO.Al_znP_O-V_znand Al_znP_O-2V_znare p-type conductive systems,and Al_znP_O-2V_znhas the highest electrical conductivity.From the analysis of reflectivity absorption rate and light transmission,Al_znP_O-2V_znhas the most excellent optical properties,followed by Al_znP_O-2V_zn,so comprehensive analysis of Al_znP_O-2V_znand Al_zn2P_O-V_znare suitable for preparing p-type and n-type conductive oxide films with good properties,respectively.