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Prof. Yafei Li’s work has been published in the journal of NANO LETTERS

GeP3: A Small Indirect Band Gap 2D Crystal with High Carrier Mobility and Strong Interlayer Quantum Confinement
Jing, Y (Jing, Yu)[ 1,3 ] ; Ma, YD (Ma, Yandong)[ 1 ] ; Li, YF (Li, Yafei)[ 2 ]*; Heine, T (Heine, Thomas)[ 1,3 ]*

[ 1 ] Univ Leipzig, Wilhelm Ostwald Inst Phys & Theoret Chem, Linnestr 2, D-04103 Leipzig, Germany
[ 2 ] Nanjing Normal Univ, Coll Chem & Mat Sci, Jiangsu Key Lab Biofunct Mat, Nanjing 210023, Jiangsu, Peoples R China
[ 3 ] Jacobs Univ Bremen, Dept Phys & Earth Sci, Campus Ring 1, D-28759 Bremen, Germany

NANO LETTERS, Mar.2017, 17(3), 1833-1838

We propose a two-dimensional crystal that possesses low indirect band gaps of 0.55 eV (monolayer) and 0.43 eV (bilayer) and high carrier mobilities similar to those of phosphorene, GeP3. GeP3 has a stable three-dimensional layered bulk counterpart, which is metallic and known from experiment since 1970. GeP3 monolayer has a calculated cleavage energy of 1.14 J m(-2), which suggests exfoliation of bulk material as viable means for the preparation of mono- and few-layer materials. The material shows strong interlayer quantum confinement effects, resulting in a band gap reduction from mono- to bilayer, and then to a semiconductor-metal transition between bi- and triple layer. Under biaxial strain, the indirect band gap can be turned into a direct one. Pronounced light absorption in the spectral range from similar to 600 to 1400 nm is predicted for monolayer and bilayer and promises applications in photovoltaics.