High-Performance Hexagonal Tellurium Thin-Film Transistor Using Tellurium Oxide as a Crystallization Retarder
Taikyu Kim, Cheol Hee Choi, Se Eun Kim, Jeong‐Kyu Kim, Jaeman Jang, Seungchan Choi, Jiyong Noh, Kwon‐Shik Park, Jeom‐Jae Kim, Soo‐Young Yoon, Jae Kyeong Jeong
Abstract
This study investigates the effect of oxygen plasma (PO) on the crystalline structure of tellurium (Te) thin films during reactive sputtering. Introduction of oxygen radicals suppresses uncontrolled rapid growth of hexagonal Te crystals, amorphizing the deposited Te thin film. This amorphous phase changes to the hexagonal phase upon alumina encapsulation. A 4-nm-thick Te transistor with a PO of 7% exhibits outstanding device performances, with a field-effect mobility up to 40.8 cm2V−1s−1 and an on/off current modulation ratio up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 10^{{6}}$ </tex-math></inline-formula> . These behaviors originate from alleviated random polycrystallinity in the corresponding thin film. However, when PO increases above 7%, amorphization progresses further, and remnant oxygen ions hamper the growth of the hexagonal phase in Te thin film. Consequently, hole transport is degraded. This study suggests tellurium oxide as a crystallization retarder for high-performance p-channel Te transistors.