Electro-mechanical-carrier coupling behaviors of piezoelectric semiconductor fibers with p–n junctions under pull-out loading

Due to their unique properties between carrier redistribution and built-in electric potential induced by external stress, piezoelectric semiconductor (PS) fibers are widely used in intelligent structures. In this paper, electromechanical coupling behaviors of PN junctions in segmented PS fiber under pull-out loading are analytically investigated. Based on the shear-lag model, the stress transfer relationship between the PS fiber and the elastic matrix is established. Closed form solutions of fiber axial stress, interfacial shear stress, electric potential, electric field, and carrier perturbation are obtained. Results show that the initial carrier concentration has a significant influence on the electromechanical coupling behaviors of segmented PS fibers compared with single homogeneous fiber. The interfacial properties of PN homojunction and heterojunction are sensitive to the concentrations of carrier doping. Besides initial doping concentration, the relevant electromechanical coupling fields can be regulated by radius ratio and external stress as well. On the basis of the linearized model, the effect of pull-out stress on the I–V curve plots under small forward-biased voltage has been investigated as well. The fundamental research will be helpful in understanding the physical mechanism of carrier regulation in PN junction fiber composites and guide for designing segmented devices in practical applications.