Carrier Screening and Selective Junction Field Control in Piezoelectric Sandwich Fibers with PNP or NPN Doping Under a Local Temperature Change

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.