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 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.