Ferroelectric-Tunable Photoresponse in α-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>In</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> Photovoltaic Photodetectors: An <i>Ab Initio</i> Quantum Transport Study
Shibo Fang, Chen Yang, Qiuhui Li, Baochun Wu, Linqiang Xu, Shiqi Liu, Jie Yang, Jiachen Ma, Jichao Dong, Ying Li, Jinbo Yang, Jing Lü
Abstract
Two-dimensional \ensuremath{\alpha}-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$ has drawn broad attention due to its high photoresponse and unique room-temperature interlocked in-plane and out-of-plane ferroelectricity with an ultralow switching electric field. Here, we investigate the photoresponse in a lateral monolayer (ML) \ensuremath{\alpha}-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$ p-i-n junction by using ab initio quantum transport simulations. The maximum photoresponses of the lateral \ensuremath{\alpha}-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$ p-i-n junction are up to 69.2 and 31.6 mA/W for the ferroelectric wurtzite and zincblende phases (shortly named WZ' and ZB') \ensuremath{\alpha}-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$, respectively, which are 8--17 times higher than that of the extensively researched graphene photodetector (4 mA/W). Remarkably, the ferroelectric photoresponses, defined as the photoresponse change ratio between the two ferroelectric states, of the lateral ML WZ' and ZB'-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$ photodetectors have average values of 127% and 121% with surprising maximum values of $2\ifmmode\times\else\texttimes\fi{}{10}^{6}\mathrm{%}$ and $1\ifmmode\times\else\texttimes\fi{}{10}^{7}\mathrm{%}$, respectively. The physical mechanism comes from the electron density redistribution altered by the atomic displacements due to the polarization switch, rather than the built-in potential change induced by the surface polarization charges. Such ferroelectric-tunable photoresponses in the \ensuremath{\alpha}-${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$ photodetector suggest a potential in the fabrication of future optical detection and storage integrated devices.