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Air-Stable In-Plane Anisotropic GeSe2 for Highly Polarization-Sensitive Photodetection in Short Wave Region

Yang, Yusi, Liu, Shun-Chang, Yang, Wei, Li, Zongbao, Wang, Yang, Wang, Xia, Zhang, Shishu, Zhang, Yun, Long, Mingsheng, Zhang, Gengmin, Xue, Ding-Jiang, Hu, Jin-Song, Wan, Li-Jun
Journal of the American Chemical Society 2018 v.140 no.11 pp. 4150-4156
activation energy, air, anisotropy, crystal structure, germanium, optical properties, oxygen, phosphorus, semiconductors
In-plane anisotropic layered materials such as black phosphorus (BP) have emerged as an important class of two-dimensional (2D) materials that bring a new dimension to the properties of 2D materials, hence providing a wide range of opportunities for developing conceptually new device applications. However, all of recently reported anisotropic 2D materials are relatively narrow-bandgap semiconductors (<2 eV), and there has been no report about this type of materials with wide bandgap, restricting the relevant applications such as polarization-sensitive photodetection in short wave region. Here we present a new member of the family, germanium diselenide (GeSe₂) with a wide bandgap of 2.74 eV, and systematically investigate the in-plane anisotropic structural, vibrational, electrical, and optical properties from theory to experiment. Photodetectors based on GeSe₂ exhibit a highly polarization-sensitive photoresponse in short wave region due to the optical absorption anisotropy induced by in-plane anisotropy in crystal structure. Furthermore, exfoliated GeSe₂ flakes show an outstanding stability in ambient air which originates from the high activation energy of oxygen chemisorption on GeSe₂ (2.12 eV) through our theoretical calculations, about three times higher than that of BP (0.71 eV). Such unique in-plane anisotropy and wide bandgap, together with high air stability, make GeSe₂ a promising candidate for future 2D optoelectronic applications in short wave region.