Thin-film electronics by atomic layer deposition

Atomic layer deposition (ALD) produces conformal films with low defects and a high degree of thickness control. Many applications leverage these properties to yield excellent dielectrics and barrier layers. In recent years, ALD has been exploited to produce thin-film transistors, in which the technique is capable of producing all of the layers required, including the semiconductor. This perspective will examine the state-of-the-art use of ALD to produce thin-film electronics, notably the zinc oxide-based thin-film transistor. It is critical that the ZnO-based semiconductor material have sufficiently high resistivity in order to yield transistors with low off current and good switching characteristics. The nature of this problem and the approaches used to address it will be discussed. The use of rapid deposition technologies, such as spatial ALD, also has a strong impact on the quality of the ZnO semiconductor. Finally, demonstrations of various thin film electronics devices and systems produced by ALD will be reviewed.