Photoinduced Synaptic Behavior of In_xTi_yO Thin Film Transistors

Abstract

Abstract Herein, In x Ti y O films are successfully deposited via the atomic layer deposition method, which involves sub‐cycles of In 2 O 3 and TiO 2 application at a growth temperature of 200 °C. In x Ti y O films are an excellent alternative to In 2 O 3 films for use in channels of thin film transistors (TFTs), and can be used to avoid issues such as metal‐like conduction characteristics and undesirable negative shifts. Adjusting the addition of TiO 2 to In 2 O 3 enables modulation of the cut‐off wavelength in the UV region. However, the addition of TiO 2 adversely affects the on‐current level. The TiO 2 content in the In x Ti y O films is optimized based on photosensitivity and current level, wherein the films are used as the channel layer in photo‐TFTs; consequently, a photo‐synaptic behavior is achieved. The In x Ti y O film‐based memory devices are programmed and erased using UV light and gate voltage, respectively, wherein deep trap sites at the interface between the InTiO and Al 2 O 3 layers facilitate the retention of charge during memory operation. The memory on/off ratio deteriorates slightly with a lapse in retention time of 4 × 10 4 s after 20 program/erase (P/E) cycles. Moreover, in the In x Ti y O‐based TFTs, excellent linearity is achieved during potentiation due to a good photo‐synaptic behavior.