Sn-Doping Enhanced Ultrahigh Mobility In1−xSnxSe Phototransistor

Two-dimensional ternary materials are attracting widespread interest because of the additional degree of freedom available to tailor the material property for a specific application. An In1−xSnxSe phototransistor possessing tunable ultrahigh mobility by Sn-doping engineering is demonstrated in this study. A striking feature of In1−xSnxSe flakes is the reduction in the oxide phase compared to undoped InSe, which is validated by spectroscopic analyses. Moreover, first-principles density functional calculations performed for the In1−xSnxSe crystal system reveal the same effective mass when doped with Sn atoms. Hence, because of an increased lifetime owing to the enhanced crystal quality, the carriers in In1−xSnxSe have higher mobility than in InSe. The internally boosted electrical properties of In1−xSnxSe exhibit ultrahigh mobility of 2560 ± 240 cm2 V−1 s−1 by suppressing the interfacial traps with substrate modification and channel encapsulation. As a phototransistor, the ultrathin In1−xSnxSe flakes are highly sensitive with a detectivity of 1014 Jones. It possesses a large photoresponsivity and photogain (Vg = 40 V) as high as 3 × 105 A W−1 and 0.5 × 106, respectively. The obtained results outperform all previously reported performances of InSe-based devices.Thus, the doping-engineered In1−xSnxSe-layered semiconductor finds a potential application in optoelectronics and meets the demand for faster electronic technology.