The electrical property modulation of insulator in metal–insulator–semiconductor–metal

The application of a material is determined by the energy barrier for charge transport between the insulator and semiconductor. For instance, a thin-film transistor (TFT) requires a large energy barrier to prohibit charge transport across the insulator–semiconductor interface, i.e., the insulator is at charge block status. Besides, there have been reports of cases where charge transport occurs across this interface, indicating the presence of a small energy barrier and suggesting that the insulator is in a charge transport state. However, the energy barrier is fixed once the device is fabricated. It is challenging to conceive that the same materials can simultaneously function as both charge transporters and blockers at the insulator–semiconductor interface, which limits its functional extension. In this study, we present and implement a mechanism for modulating the energy barrier at the insulator–semiconductor interface using parallel connections of metal–insulator–metal (MIM) with metal–insulator–semiconductor–metal (MISM) structures, namely the MIM/MISM structure. The charge transport and charge block functions are achieved even with the same oxide SiO2 and semiconductor InGaZnO4. Furthermore, we demonstrate electrical property transitions from charge transport to block states in one MIM/MISM device. We discuss how such transitions impact TFTs’ electrical properties and show that they can be utilized to enhance surface potential increments in TFTs. As a result, we achieve a subthreshold swing value of 51 mV/decade, breaking free from Boltzmann tyranny.