Field-Effect Device Using Quasi-Two-Dimensional Electron Gas in Mass-Producible Atomic-Layer-Deposited Al2O3/TiO2 Ultrathin (??10 nm) Film Heterostructures

We report the field-effect transistors using quasi-two-dimensional electron gas generated at an ultrathin (similar to 10 nm) Al2O3/TiO2 heterostructure interface grown via atomic layer deposition (ALD) on a SiO2/Si substrate without using a single crystal substrate. The 2DEG at the Al2O3/TiO2 interface originates from oxygen vacancies generated at the surface of the TiO2 bottom layer during ALD of the Al2O3 overlayer. High-density electrons (similar to 10(14) cm(-2)) are confined within a similar to 2.2 nm distance from the Al2O3/TiO2 interface, resulting in a high on-current of similar to 12 mu A/mu m. The ultrathin TiO2 bottom layer is easy to fully deplete, allowing an extremely low off-current, a high on/off current ratio over 10(8), and a low subthreshold swing of similar to 100 mV/decade. Via the implementation of ALD, a mature thin-film process can facilitate mass production as well as three-dimensional integration of the devices.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, & Future Planning (grant no. 2015R1A5A1037548). This research was also supported by the Basic Science Research Program through the NRF funded by the Ministry of Education (grant nos. 2018R1D1A1B07046071 and 2018R1D1A1B07043427) and by the Korea Basic Science Institute (grant no. T38603)