High‐Mobility p‐Channel Thin‐Film Transistors Based on Polycrystalline GeSn

Abstract GeSn has gained significant interest as a material for next‐generation electronic devices, including thin‐film transistors (TFTs) because of its excellent electronic properties. In this study, high‐quality polycrystalline GeSn thin films are fabricated on glass substrates and fabricated high‐performance TFTs. A bilayer structure with modulated deposition temperatures simultaneously suppressed nucleation and promoted growth, thereby enabling the formation of large‐grained GeSn layers. The sample exhibited high Hall hole mobility (230 cm 2 V −1 s −1 ) and low hole concentration (4.1 × 10 17 cm −3 ), which are the best electrical properties for polycrystalline Ge‐based thin films applicable for accumulation‐mode TFTs. The fabricated TFTs demonstrated field‐effect mobility of up to 250 cm 2 V −1 s −1 . This value is not only the highest for a polycrystalline Ge‐based TFT, but also the highest for a p‐channel TFT fabricated in a low‐temperature process (≤500 °C). Thus, this study represents an important step toward the realization of high‐performance TFTs using GeSn, which is a significant achievement that can contribute to the next generation of electronics technologies.