Theoretical Study Of Elastic Field And Piezoelectric Field In Nano-heterostructures

The piezoelectric semiconductor materials,such as GaAs,InP,SiGe,etc.,are suitable for high speed,high frequency,high temperature and high power electronic devices with excellent performance,and they are also excellent materials for high-performance microwave devices and circuits.They are widely used in aerospace,satellite communications and other fields,which are of great significance to the development of aerospace engineering.In recent years,with the development of metal-organic chemical vapor deposition technology and molecular beam growth technology,the development and application of piezoelectric nano-heterostructures have been deepened.Compared with macroscopic piezoelectric materials,due to the inclusion in the piezoelectric heterostructure where the nano-particle has a very large surface-volume ratio,the surface microstructure presents unique physical properties which is enough to change the performance of the material.Therefore,between the interface of the particle and matrix,surface/interface effect cannot be neglected as classical mechanics,and it shall be deemed to have different attributes from the particle and matrix.It also influences the force-electricity coupling characteristics of piezoelectric materials.In view of the above phenomena,the interface effect on the piezoelectric property and the coupling effect between elastic field and piezoelectric field are studied in detail.This project mainly carries out the following work:1.Based on the basic concept and calculation method of surface excess energy,the basic concept of surface elastic properties is introduced.The surface elastic properties of some materials are obtained by molecular dynamics simulations.2.To establish a model for quantum dots with isotropic materials in nano-heterostructures,Lamé constants of the interface effect are introduced to analyze the elastic and piezoelectric fields.The analytical expressions of elastic field and piezoelectric field in nano-heterostructures are deduced under the influence of interface effect.By setting the heterogeneous structure as GaAs/InAs,the numerical solution is given,and the interface effect on the piezoelectric field is obtained.3.To establish a model for a quantum wire with anisotropic materials in nano-heterostructures,the interfacial elasticity coefficient is introduced into the calculation model.The analytical expressions of elastic field and piezoelectric field in nano-heterostructures are deduced under the influence of interface effect.The heterostructure is set as InAs/InP for numerical solution,and the interface effect on the piezoelectric field is obtained.4.To study the effect of sequential-coupling and full-coupling on the results in nano-heterostructures.For weak piezoelectric coupling material(GaAs)and strong piezoelectric coupling material(AlN),the methods of sequential-coupling and full-coupling numerical calculation are carried out at the same time by comparing four groups of data to analyze the influence on the result of calculations.The interface effect is introduced into the full-coupling numerical calculation to analyze the influence on the result of the effective dielectric constant of the nano-heterostructure with multiple quantum dots.