This work presents an ultrahigh gain InSe-based photodetector by using a novel approach called the surface oxidation doping (SOD) technique. The carrier concentration of multilayered two-dimensional (2D) InSe semiconductor surface has been modulated by controlling the formation of a surface oxide layer. The SOD through surface charge transfer at the interface of the oxide/2D InSe semiconductor heterostructure can lead to the creation of a vertical built-in potential and band bending as a result of the carrier concentration distribution gradient. The internal electric field caused by the formation of a carrier concentration gradient in InSe layers can facilitate charge separation of photogenerated electron–hole pairs under light illumination. Consequently, the record high photoresponsivities of InSe-based photodetector with ∼5 × 10⁶ A/W at the excitation wavelength of 365 nm and 5 × 10⁵ A/W at the wavelength of 530 nm can be obtained, outperforming the majority of photodetectors based on other 2D materials, such as graphene, MoS₂, and even highly sensitive multilayer GaTe and In₂Se₃ flakes. The approach based on SOD induced efficient photogenerated charge separation can be also applied to other 2D layered semiconductors.

中文翻译：

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表面氧化掺杂可增强超高增益硒化铟光电探测器的光生载流子分离效率

这项工作通过使用一种称为表面氧化掺杂（SOD）技术的新颖方法，提出了一种基于InSe的超高增益光电探测器。多层二维（2D）InSe半导体表面的载流子浓度已通过控制表面氧化物层的形成进行了调节。氧化物/ 2D InSe半导体异质结构的界面上通过表面电荷转移的SOD可能会由于载流子浓度分布梯度而导致垂直内置电位的产生和能带弯曲。在InSe层中形成载流子浓度梯度所引起的内部电场可以促进光照射下光生电子-空穴对的电荷分离。因此，具有约5×10的基于InSe的光电探测器具有创纪录的高光响应性在365 nm的激发波长下可达到⁶ A / W，在530 nm的波长下可获得⁵ A / W。5 A / W优于大多数基于其他2D材料（例如石墨烯，MoS ₂甚至更高）的光电探测器。敏感的多层GaTe和In ₂ Se ₃薄片。基于SOD诱导的有效光生电荷分离的方法也可以应用于其他2D分层半导体。