Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

In 2009, a crystalline oxide semiconductor with a layered structure, which we refer to as c ‐axis–aligned crystalline indium‐gallium‐zinc oxide ( CAAC ‐ IGZO ), was first discovered. CAAC ‐ IGZO has a peculiar crystal structure in which clear grain boundaries are not observed despite high c ‐axis alignment and absence of a ‐ b plane alignment. When compared to a Si field‐effect transistor ( FET ), a metal‐oxide‐semiconductor ( MOS ) FET , utilizing CAAC ‐ IGZO , presents lower off‐state current (on the order of yA [10 −24 A]). These unique characteristics allow CAAC ‐ IGZO to realize devices with low power consumption. With the emerging era of artificial intelligence, wherein power saving becomes more significant, CAAC ‐ IGZO has attracted attention as a potential replacement for Si. This paper describes the characteristics and potentials of CAAC ‐ IGZO for the development of memory devices with unprecedented functions.