Metal / Oxide Interface Control for the Turn-on Voltage Change of Oxide Thin-film Diodes*

As the size of electronic devices has been reduced, there is a growing need for current to flow through an insulating thin-film. Although, due to the inherent energy band properties of most insulating materials, the transport of charge carriers through an insulator remains a limited process window. Recently, we have presented a technique for transferring electrons stably through a thick insulator film (over 100 nm) in metal / insulator / oxide semiconductor / metal (MIOSM) contact structures. Depending on the interface charge state of the oxide semiconductor film, the current passes uni-directionally as a conventional diode. Herein, we propose a method of controlling the turn-on voltage in MIOSM structure, based on the control of the interface contact resistance between the oxide semiconductor and the metal. When Al and Ag were deposited on the IGZO, the turn-on voltage was adjustable from 0V to 14.4V due to a difference in the respective interface contact resistance. We also demonstrated that the turn-on voltage can be precisely controlled by changing the IGZO thickness in contact with Ag.