This paper details the thermal–mechanical–electrical response of a piezoelectric semiconductor (PS) composite fiber composed of a PS layer and two piezoelectric layers under local temperature change. The phenomenological theory of thermal piezoelectric semiconductors (PSs) is adopted to obtain the analytical solution for each field in the composite fiber under local temperature change. Our findings reveal that such temperature fluctuations induce local polarization, leading to the formation of local potential barriers and potential wells that effectively impede the flow of low-energy electrons along the fiber. Furthermore, the initial carrier concentration and geometric parameters of the composite fiber exert significant influence on its individual fields. The results contribute to the structural design and practical application of piezoelectric semiconductor devices.

Multiferroic composite semiconductor fibers enable non-contact magnetic control but may also operate under spatially nonuniform thermal conditions. This study develops a one-dimensional analytical model for a symmetric CoFe₂O₄/ZnO/CoFe₂O₄ fiber subjected to local magnetic and temperature fields with independently prescribed widths. The model combines piezomagnetic, piezoelectric, pyroelectric, thermoelastic, and semiconductor effects and provides closed-form solutions for the electric potential, electric field, polarization, and electron concentration perturbation. Local magnetic and thermal inputs generate localized potential barriers and wells through distinct pathways. Where the excitation regions overlap, their contributions may reinforce, compete with, or partially cancel each other. The initial electron concentration affects the carrier-screening strength and spatial localization of the electrical response, whereas the layer-thickness ratio influences the competition between piezomagnetic actuation and piezoelectric conversion. An independent finite-element calculation closely reproduces the analytical potential distribution for the baseline case. This study clarifies the interaction between the magnetic and thermal contributions to open-circuit carrier redistribution and provides a field-distribution baseline for future biased, contact-resolved transport analyses of multiferroic micro- and nanostructures.

Piezoelectric semiconductor PN junctions hold considerable promise for self-powered sensing, flexible electronics, energy harvesting, photodetection, and multifunctional micro/nanodevices. A local temperature change couples the built-in electrical response of the PN doping interface with the thermally induced response at the boundaries of the heated region, thereby modifying the electric potential, electric field, electric displacement, and carrier distributions near the junction. To elucidate this coupling mechanism, a one-dimensional three-interface analytical model is developed for a piezoelectric semiconductor PN junction subjected to a local temperature change. The fiber is divided into cold P-type, heated P-type, heated N-type, and cold N-type regions, and the coupled response is determined using piecewise analytical solutions together with open-circuit end conditions, interface continuity conditions, global carrier-conservation constraints, and reference-point conditions. Within a linear small-perturbation framework for an ideal zero-thickness homojunction, numerical results show that the PN doping interface governs the baseline distributions of the built-in potential and electric field, whereas the temperature interfaces generate additional electric fields through temperature-induced electric-displacement compensation, leading to localized redistribution of holes and electrons. For the baseline ZnO case with a 0.5 K temperature increment, the potential span is 9.124 mV, the peak electric-field magnitude is 48.43 kV m⁻¹, and the maximum carrier perturbation is 0.180 of its regional reference concentration. Independent Galerkin finite-element calculations agree with the analytical solution, with a maximum normalized discrepancy of 0.553% on the finest mesh. The temperature-change amplitude, heated-region half-width, reference carrier-concentration level, P/N doping asymmetry, effective dielectric constant, and effective thermal electric-displacement coefficient modify the potential transition, electric-field peaks, and carrier-screening range near the junction. These results reveal the coupled interaction between the local temperature interfaces and the PN doping interface and provide a theoretical basis for thermally regulating piezoelectric semiconductor junction devices under localized thermal loading.

Carrier screening and observation geometry determine how a local magnetoelectric response contributes to a potential-difference readout. This study develops a finite-length one-dimensional analytical model for a weak PN-junction piezoelectric-semiconductor fiber between magnetostrictive layers subjected to a localized magnetic-field increment about a prescribed bias. Cross-sectional force balance, two-carrier drift–diffusion, blocking end conditions, and interface continuity yield a four-region solution that separates the junction reference from the magnetic increment. In the representative weak-junction case, the end-to-end difference is about 1% of the peak local magnetically induced potential, whereas observation pairs at the field-region edges and near the junction give differences about 200 and 50 times larger than the end-to-end value. For equal screening and a step field, the response of a fixed interior pair peaks when the field-region edges reach the observation points. Uniformly doped and symmetric weak-junction controls have identical magnetic increments under equal screening despite their different reference fields. Layer thickness modifies both magnetic conversion and carrier screening. The resulting continuum-model relations identify how excitation width, screening length, and observation position jointly govern internal magnetic-field readout.

Spatially selective thermal regulation of multijunction piezoelectric structures requires the control of both the local junction response and coupling between neighboring junctions. A finite-length analytical model is developed for a symmetric piezoelectric sandwich fiber with PNP or NPN doping under a prescribed local temperature change. Within a static, closed, one-dimensional weak-junction approximation, the solution separates the reference junction field from the thermally induced polarization response and accounts for carrier screening and global carrier conservation. Finite-element and nonlinear drift calculations assess solution accuracy and the carrier linearization. Centered heating reduces one junction field while enhancing the other, whereas independently controlled thermal regions enable simultaneous point cancelation through their differential response. In the representative weak-junction case, opposite temperature increments of approximately 0.0165 K cancel the two-junction point fields; minimizing the field over finite junction neighborhoods instead leaves approximately 30% of the reference root-mean-square field. Fixed-interval potential differences further show that point cancelation does not eliminate the electrical response across a junction neighborhood. Thermal spreading and constitutive uncertainty shift the required temperature settings. The prescribed carrier populations do not represent dark-equilibrium ZnO at room temperature. The resulting control relations characterize an idealized weak-junction system, rather than a validated semiconductor device, and provide conditional guidance for thermal-source placement and control-target selection.