Zhang C Y, Yu M
Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, United States of America.
Nanotechnology. 2018 Mar 2;29(9):095703. doi: 10.1088/1361-6528/aaa63b.
Atomic layers of GaP and InP binary compounds with unique anisotropic structural, electronic and mechanical properties have been predicted from first-principle molecular dynamics simulations. These new members of the phosphide binary compound family stabilize to a sandwiched two-dimensional (2D) crystalline structure with orthorhombic lattice symmetry and high buckling of 2.14 Å-2.46 Å. Their vibration modes are similar to those of phosphorene with six Raman active modes ranging from ∼80 cm to 400 cm. The speeds of sound in their phonon dispersions reflect anisotropy in their elastic constants, which was further confirmed by their strong directional dependence of Young's moduli and effective nonlinear elastic moduli. They show wide bandgap semiconductor behavior with fundamental bandgaps of 2.89 eV for GaP and 2.59 eV for InP, respectively, even wider than their bulk counterparts. Such bandgaps were found to be tunable under strain. In particular, a direct-indirect bandgap transition was found under certain strains along zigzag or biaxial orientations, reflecting their promising applications in strain-induced bandgap engineering in nanoelectronics and photovoltaics. Feasible pathways to realize these novel 2D phosphide compounds are also proposed.
通过第一性原理分子动力学模拟预测了具有独特各向异性结构、电子和机械性能的GaP和InP二元化合物的原子层。磷化物二元化合物家族的这些新成员稳定为具有正交晶格对称性和2.14 Å - 2.46 Å高屈曲的夹心二维（2D）晶体结构。它们的振动模式与磷烯相似，有六种拉曼活性模式，范围从~80 cm到400 cm。它们声子色散中的声速反映了其弹性常数的各向异性，杨氏模量和有效非线性弹性模量的强烈方向依赖性进一步证实了这一点。它们表现出宽带隙半导体行为，GaP和InP的基本带隙分别为2.89 eV和2.59 eV，甚至比它们的体相材料更宽。发现这种带隙在应变下是可调的。特别是，在沿锯齿形或双轴取向的某些应变下发现了直接 - 间接带隙转变，这反映了它们在纳米电子学和光伏的应变诱导带隙工程中的应用前景。还提出了实现这些新型二维磷化物化合物的可行途径。
