Ultrahigh Sensitivity Strain Sensor Based On Piezotronic Transistor

With the increasingly serious energy crisis phenomenon of the word and the growing awareness of environmental protection,people in modern science and technology in addition to the use of chemical energy,wind,solar and other large scale of energy.In micro-nano electronics,we also need energy to sustain energy supply to achieve a variety of complex functions.However,in micro-electronic systems,the size of the system is almost determined by the size of the power supply.We urgently need to be able to continuously supply the system with energy in its unique environment.Scientists have found that materials with wurtzite structures have both piezoelectric and semiconductor properties.Through the coupling of the two properties,the self-energy technology in micro and nano devices is realized,which opens up the innovative field of piezoelectric electronics.Due to polarization of ions in crystals with noncentral symmetry,such as ZnO,GaN,and InN,a piezoelectric potential(piezopotential)is created in the crystal when stress is applied.Electronics fabricated using the inner-crystal piezopotential as a gate voltage to tune or control the charge transport behavior across a metal/semiconductor interface or a p–n junction are called piezotronics.This is different from the basic design of complementary metal oxide semiconductor(CMOS)field-effect transistors and has applications in force and pressure triggered or controlled electronic devices,sensors,microelectromechanical systems(MEMS),human-computer interfacing,nanorobotics,and touch-pad technologies.Here,the theory of charge transport in piezotronic devices is investigated.In addition to presenting the formal theoretical frame work,analytical solutions are presented for cases including metal-semiconductor contact and p–n junctions under simplified conditions.Piezoelectric materials have a wide range of applications in sensors,actuators,and energy harvesting.The most well-known piezoelectric materials are PZT and quartz.The insulating and non-semiconductive nature of these materials limits their applications in electronic and photonic devices.Recently,much attention has been focused on piezoelectric semiconductor materials in the wurtzite family,including ZnO,GaN,In N,and CdS.Due to the coupling of piezoelectric and semiconducting properties,nano-and microwires of piezoelectric semiconductors have been used as basic building blocks for fabricating innovative devices,such as nanogenerators,piezoelectric field-effect transistors,piezoelectric diodes,piezoelectric chemical sensors,and piezo-phototropic devices.Furthermore,based on the piezoelectric-semiconductor properties,a new field of piezotronics has been created,which uses the effect of the piezoelectric potential created in the crystal for controlling or tuning the charge carrier transport characteristics to fabricate mechanical electronic devices,with potential applications in microelectromechanical systems,nanorobotics,human–computer interfacing,and sensors.In this paper,the piezoelectric properties of materials,the effect of piezoelectric charge on the p-n junction region,the simulation of piezoelectric p-n junction diodes and the characteristics of bipolar transistors are analyzed.A new electronic device,the piezoelectric bipolar transistor,is simulated by COMSOL software.Using the DC amplification effect of the n-p-n bipolar transistor,the strain applied can change the characteristics of carrier transmission in p-n junction.The combination of the two leads to the formation of a nanoscale range in which the current amplification effect of bipolar transistors is greatly increased by strain,and the principle of electronic devices with ultra-high sensitivity is developed.This provides a theoretical basis for the innovative design of new nano piezoelectric devices in the future.