(Correspondent: Liu Shuhai and Zhao Binzheng) Advanced Materials(Impact Factor is 25.806), international top academic Journal in materials, reported “Piezotronic Tunneling Junction Gated by Mechanical Stimuli”, the latest research of School of Advanced Materials and Nanotechnology, Xidian University, on October 23. Doctoral Candidate Liu Shuhai, guided by Professor Qin Yong,isthe lead author, and Xidian University is the lead unit.

In the classical case, the carriers of which energy isbelow the height ofthe barrier will be completely confined by the barrier. However, according to the theory of quantum mechanics, the carriers have wave behavior. When the barrier is thin enough, the carrier will have a certain probability of tunneling through the barrier. Tunneling rate is exponentially related to the barrier shape and the carrier concentration on both sides of the barrier, which makes the Tunneling junction usually have a large tunneling resistance on-off ratio (as high as 103-105). At the same time, because the tunneling is a phenomenon of carrier effect, the time of carriers passing through the barrier is not controlled by the conventional transit time, but by the quantum transition rate per unit time, so the tunnel junction usually has a faster response rate. Based on this, Quantum tunneling devices usually have high on-off ratio and rapid response.Esaki diode, Josephson superconducting junction (STJ), magnetic tunnel junction (MTJ) and ferroelectric tunnel junction (FTJ) are well-known examples, and received extensive attention.

Up to now, most of the work focuses on the use of electric or magnetic fields to directly control the barrier height or the carrier permissive states on both sides of the barrier, so as to realize the control of the electrical transport properties of tunnel junction. The mechanism of using mechanical driving force to control tunnel junction has not yet appeared, the self-adaption and seamless connection between electrical signal and mechanical motion is key for human-machine interface, intelligent skin and robot technology. If the tunnel junction with stress control can be developed, together with tunnel junction’s excellent properties, it will be of great significance in the fields of human-machine interface and electronic skin. Therefore, it is of great value to design a novel scheme to control the quantum tunneling effect by mechanical driving force.

Piezotronic Tunneling Junction

(a-d) ) Control Principles; e) StructureSchematics; f)I-V Characteristic Curve

Research on Dynamic Imaging Properties of Piezotronic Tunneling Junction

(a)Force Imaging Test under Different Situations; b)Force Imaging Test at Different Scan Speed; c-d)dynamic response time analysis of piezotronic tunneling junction)

During the research, under the guidance of Professor Qin Yong and Academician Wang Zhonglin of Beijing Institute of Nanoenergy and Nansystem, Chinese Academy of Sciences, Liu Shuhai, Wang Longfei and Feng Xiaolong have successfully designed and fabricated a novel piezoelectric tunneling junction (PTJ) with heterostructure of metal / insulator / piezoelectric semiconductor. The height and width of the barrier can be simultaneously polarized by piezoelectric polarization charge, resulting inhigh sensitivity, giant switching, and fast response. Moreover, tunnel piezoelectric electronics with insulating layer of various thicknesses is systematically investigated. This study not only demonstrated the principle of mechanical control of quantum tunneling by piezoelectric effect, but also displayed the potential applications of piezotronic tunneling junction in the fields of ultrasensitive press sensor and electronic skin.

Link to relative research:http://doi.org/10.1002/adma.201905436