A Study of Metal Influence on Widening Operating Voltage of Oxide Thin Film Diodes

Abstract

Recently, a new type of oxide thin-film diode based on hetero-interface between oxide semiconductor and insulator has been reported. The metal / insulator / oxide semiconductor / metal structured MISM diode exhibits excellent rectification ratio and stable current behavior. In particular, the on-current level can be controlled by adjusting the dielectric constant and thickness of the insulators. Controlling of turn-on voltage and expanding operating window are critical features for making more diverse MISM diodes. However, these have not yet been studied. Thus, we demonstrate a simple process for the first time that can control the turn-on voltage of the MISM diode. We propose engineering the interface between the top metal and oxide semiconductor layers. The turn-on voltage of MISM diodes has been found to shift significantly depending on the oxide semiconductor and top electrode material combination. Using aluminum for the top metal of the diode, the turn-on voltage is 0 V, which is significantly different from 14.4 V when using silver. Moreover, when titanium was deposited first before silver, the turn-on voltage shows 0 V. Therefore, we suggest a new fundamental technique to expand the operating window of the MISM diode.