Perpendicular Optical Reversal of the Linear Dichroism and Polarized Photodetection in 2D GeAs

• Published in: ACS nano 2018-12, Vol.12 (12), p.12416-12423
• Main Authors: Zhou, Ziqi, Long, Mingsheng, Pan, Longfei, Wang, Xiaoting, Zhong, Mianzeng, Blei, Mark, Wang, Jianlu, Fang, Jingzhi, Tongay, Sefaattin, Hu, Weida, Li, Jingbo, Wei, Zhongming
• Format: Article
• Language: English
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.8b06629

The ability to detect linearly polarized light is central to practical applications in polarized optical and optoelectronic fields and has been successfully demonstrated with polarized photodetection of in-plane anisotropic two-dimensional (2D) materials. Here, we report the anisotropic optical characterization of a group IV–V compound-2D germanium arsenic (GeAs) with anisotropic monoclinic structures. High-quality 2D GeAs crystals show the representative angle-resolved Raman property. The in-plane anisotropic optical nature of the GeAs crystal is further investigated by polarization-resolved absorption spectra (400–2000 nm) and polarization-sensitive photodetectors. From the visible to the near-infrared range, 2D GeAs nanoflakes demonstrate the distinct perpendicular optical reversal with a 75–80° angle on both the linear dichroism and polarization-sensitive photodetection. Obvious anisotropic features and the high dichroic ratio of I pmax /I pmin ∼ 1.49 at 520 nm and I pmax /I pmin ∼ 4.4 at 830 nm are achieved by the polarization-sensitive photodetection. The polarization-dependent photocurrent mapping implied that the polarized photocurrent mainly occurred at the Schottky photodiodes between electrode/GeAs interface. These experimental results are consistent with the theoretical calculation of band structure and band realignment. Besides the excellent polarization-sensitive photoresponse properties, GeAs-based photodetectors also exhibit rapid on/off response. These results demonstrate that the 2D GeAs crystals have promising potential for polarization optical applications.