Hydrogen diffusion and its electrical properties variation as a function of the IGZO stacking structure

The oxygen vacancies and hydrogen in oxide semiconductors are regarded as the primary sources of charge carriers and various studies have investigated the effect of hydrogen on the properties of oxide semiconductors. However, the carrier generation mechanism between hydrogen and oxygen vacancies in an a-IGZO semiconductor has not yet been clearly examined. In this study we investigated the effect of hydrogen and the variation mechanisms of electrical properties of a thin film supplied with hydrogen from the passivation layer. SiO_x and SiN_x, which are used as passivation or gate insulator layers in the semiconductor process, respectively, were placed on the top or bottom of an a-IGZO semiconductor to determine the amount of hydrogen penetrating the a-IGZO active layer. The hydrogen diffusion depth was sufficiently deep to affect the entire thin semiconductor layer. A large amount of hydrogen in SiN_x directly affects the electrical resistivity of a-IGZO semiconductor, whereas in SiO_x, it induces a different behavior from that in SiN_x, such as inducing an oxygen reaction and O–H bond behavior change at the interface of an a-IGZO semiconductor. Moreover, the change in electrical resistivity owing to the contribution of free electrons could be varied based on the bonding method of hydrogen and oxygen.