Preface to the Special Section on Piezotronics

For wurtzite structures that have noncentral symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a strain. Owing to the semiconducting and piezoelectric properties of the wurtzite family, the strain-created inner-crystal piezopotential can serve as a “gate voltage” that can effectively tune/control the charge transport across an interface/junction, which has been named the piezotronic effect ; electronics that are fabricated based on such a mechanism are coined as piezotronics , [ 1–3 ] with applications in force/pressure triggered/ controlled electronic devices, sensors, logic units and memories. Piezotronics is likely to serve as “mechanosensation” for directly interfacing biomechanical action with silicon-based technology and active fl exible electronics, which responses/feeds-back/generates electronic control signals in a corresponding substrate-induced mechanical deformation. By using the piezotronic effect, it is shown that the optoelectronic devices fabricated using wurtzite materials can have a much enhanced performance as solar cell, photon detector, or light emitting diode. [ 2 , 3 ]