Degradation mechanism of amorphous IGZO-based bipolar metal-semiconductor-metal selectors

Abstract

To enable high-density cross-point arrays of magnetic memory a suitable access device is necessary. A promising candidate for this role is a metal-semiconductor-metal (MSM) tunneling device. In this work, the operation of an ultrathin Pt\6nm a-IGZO\Pt stack as an MSM selector is discussed. The focus is given to understanding the breakdown mechanism at high current regime, which prevents it from reaching the target current density. The breakdown is preceded by a gradual degradation process, which is manifested as an increase in high-field current after prolonged stress. This effect is recoverable - current returns to original value after sufficient delay time. Based on these observations, we propose a mechanism, where increased high-field current can be explained as a decrease in Schottky barrier height arising from stress-induced increase in oxygen vacancies.