Sn-Doping Enhanced Ultrahigh Mobility In_1–<i>x</i>Sn_<i>x</i>Se Phototransistor

Abstract

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 In_1-<i>x</i>Sn_<i>x</i>Se phototransistor possessing tunable ultrahigh mobility by Sn-doping engineering is demonstrated in this study. A striking feature of In_1-<i>x</i>Sn_<i>x</i>Se 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 In_1-<i>x</i>Sn_<i>x</i>Se 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 In_1-<i>x</i>Sn_<i>x</i>Se have higher mobility than in InSe. The internally boosted electrical properties of In_1-<i>x</i>Sn_<i>x</i>Se 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 In_1-<i>x</i>Sn_<i>x</i>Se flakes are highly sensitive with a detectivity of 10¹⁴ Jones. It possesses a large photoresponsivity and photogain (<i>V</i>_g = 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 In_1-<i>x</i>Sn_<i>x</i>Se-layered semiconductor finds a potential application in optoelectronics and meets the demand for faster electronic technology.