Abstract:

It is discovered that the product of the current and the electric field in a PN junction should be regarded as the rate of work (power) done by the electric field force on moving charges (hole current and electron current), which was previously misinterpreted as solely a Joule heating effect. We clarify that it is exactly the work done by the electric field force on the moving charges to stimulate the emergence of non-equilibrium carriers, which triggers the novel physical phenomena. As regards to Joule heat, we point out that it should be calculated from Ohm's law, rather than simply from the product of the current and the electric field. Based on this understanding, we conduct thorough discussion on the role of the electric field force in the process of carrier recombination and carrier generation. The thermal effects of carrier recombination and carrier generation followed are incorporated into the thermal equation of energy. The present study shows that the exothermic effect of carrier recombination leads to a temperature rise at the PN interface, while the endothermic effect of carrier generation causes a temperature reduction at the interface. These two opposite effects cause opposite heat flow directions in the PN junction under forward and backward bias voltages, highlighting the significance of managing device heating phenomena in design considerations. Therefore, this study possesses referential significance for the design and tuning on the performance of piezotronic devices.

Key words: piezoelectric semiconductor (PS), work done by electric field force, thermal effect, piezotronic device, resistivity, conductivity