Analysis On Coupling Between Elastic Waves And Charge Carriers In Piezoelectric Semiconductor Structures

With the rapid development of artificial intelligence,information technology and nano energy,modern electronic devices which are moving towards miniaturization,functional diversification,human-computer interaction and self-energy supply,requires a new generation of semiconductor materials and structures with completely new functions.The piezoelectric semiconductor materials and structures have been widely used in the field of piezotronic device due to its piezoelectric and semiconducting coupling.In this paper,the interaction between the carrier and the electromechanical field in the piezoelectric semiconductor structure is deeply analyzed,and the propagation law of the coupling wave in the piezoelectric semiconductor structure is revealed,some meaningful research results have been obtained.These research results include:(1)Discard the small disturbance hypothesis,the nonlinear governing equation of the carrier concentration in the n-type Zn O nanowire is established,and the effect of the carrier accumulation on the electromechanical field across the nanowire is studied,the phenomenon of electric leakage of Zn O nanowire generator is found.In order to reduce the shielding effect caused by carrier accumulation and obtain the maximum output energy,we put forward the requirement to reduce the doping concentration,and optimized the electrode configuration according to the distribution characteristics of the boundary potential and the electric displacement.(2)In order to solve the problem of n-type Zn O nanowire generator with low doping concentration,taking the effect of both electron and hole into consideration,a nonlinear governing equation about electric potential in Zn O harvesting structure is established.The distribution law of electric field in the cross section under different doping concentration is obtained,the leakage phenomenon caused by semiconductor characteristics is explained,and the proper range of carrier concentration doping is given.(3)Under the condition of linear hypothesis,the propagation law of machanical-electriccarrier disturbance of piezoelectric semiconductor beam under the impact of end load is studied.It is found that the propagation speed of carrier disturbance in the structure is much faster than that of electromechanical coupling vibration,which indicates that the propagation speed of electric signal is much faster than that of mechanical signal.(4)In the case of small perturbation linear approximation,the secular equation of coupled waves in a piezoelectric semiconductor structure is established,and two kinds of wave velocities and their attenuation factors are obtained.by means of polarization vector analysis,these two kinds of waves are distinguished as electromechanical coupling wave and electric field-carrier coupling wave,and their propagation and attenuation characteristics are analyzed on three characteristic time scales.It is found that the latter is associated fluctuation which is induced by the interaction between the polarized electric field and the carriers on the electromechanical coupling wave front,which is easily screened by the dielectric relaxation effect,so it can only travel at the micron or sub-micron scale.At the same time,in order to enhance the coupling effect between the electromechanical field and the carrier,we put forward the concept of energy conversion rate and give the corresponding optimization range.(5)In the case of introducing a static biasing field,the thermal balance equation of the piezoelectric semiconductor structure is established,and the distribution law of electric potential and carrier concentration caused by the biasing field is analyzed.On this basis,a small-amplitude vibrational elastic wave is applied to the piezoelectric semiconductor structure,and the characteristics of the influence of the biasing field on the propagation law of the coupled wave are deeply analyzed,and the acoustic gain/attenuation mechanism caused by the biasing field is pointed out.In this paper,the mechanism of multi-field coupling and the regulation law of electromechanical in piezoelectric semiconductor structures are studied in depth.The research results are of great theoretical significance and practical value for the design and application of piezotronics devices.This is of great theoretical significance to the development of elastic wave theory and to the research,development and application of new piezoelectric devices.