Origin of Ambipolar Behavior in p-Type Tin Monoxide Semiconductors: Impact of Oxygen Vacancy Defects
Taikyu Kim, Min Jae Kim, Ho‐Chang Lee, Hongwei Xu, Cheol Hee Choi, Jeong‐Kyu Kim, Jae Kyeong Jeong
Abstract
In this study, we examine the effect of oxygen vacancies ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> ) near the back surface of p-type tin monoxide (SnO) semiconductors on the device performance of its thin-film transistors (TFTs). Non-stoichiometry of the SnO surface layer was controlled through oxidant exposure conditions during alumina (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) growth using plasma-enhanced atomic layer deposition (PEALD). During the initial period of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> deposition, trimethylaluminum precursors absorbed oxygen from the SnO layer and created the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> , which can form a V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> -rich region at the Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /SnO interface. By modulating the oxygen plasma density during the PEALD process, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> was effectively controlled, allowing the electrical characteristics to transition from ambipolar behavior to p-channel only conduction. This study demonstrates the importance of the back surface of SnO, suggesting a new perspective of ambipolar behavior in p-type SnO semiconductors.