In this paper, a nonlinear magneto-thermo-mechanical coupling theoretical model related to the coupled extensional and flexural deformation working modes of controllable heterogeneous PN junction devices is established, and the screening effect caused by the doping levels of the initial mobile carrier concentrations, the surface effect and critical thickness of the average electric field, and the active manipulation mechanism and evolution law for the deformation-polarization-carrier coupling fields are investigated. The results show that a relatively moderate doping level can effectively improve the transport behaviors and distribution characteristics of the electrons and holes in the PN junction. When the thickness of the PN junction device is reduced to a critical value, the size-dependent behavior caused by the surface effect owing to the average electric field difference is obvious. The working performance of the controllable giant magnetostrictive Terfenol-D based heterogeneous PN junction device can be improved evidently when the Terfenol-D layers of the laminated nanoplate devive are subjected to the changing operating temperature, applied external magnetic field, or pre-stress stimuli. These findings can provide effective guidance for the explanation of the nonlinear magneto-mechanical-thermo coupling active manipulation mechanism for induced deformation-polarization-carrier coupling fields, as well as the experimental design of Terfenol-D based heterogeneous PN junction nanodevices.