Informal Phosphorene Symposium

Black phosphorous (BP) is is recently unveiled as a promising two-dimensional direct bandgap semiconducting material. Here, we report the ambipolar field effect transistor behavior of multilayers of BP with ferromagnetic tunnel contacts. We observe a reduced of Schottky barrier < 50 meV by using TiO2/Co contacts, which could be further tuned by gate voltages. Eminently a good transistor performance is achieved in BP devices, with drain current modulation on the order of four to six orders of magnitude. The charge carrier mobility is found to be 155 and 0.18 cm V s for holes and electrons respectively at room temperature. Furthermore, magnetoresistance calculations reveal that the resistances of the BP device with applied gate voltages are in the appropriate range for injection and detection of spin polarized holes. Our results demonstrate the prospect of engineering BP nanolayered devices for efficient nanoelectronic and spintronic applications. 33. Strain enhanced anisotropic thermoelectric performance of Black Phosphorus Guangzhao Qin, Zhenzhen Qin, Sheng-Ying Yue, Hui-Juan Cui, QingRong Zheng, Qing-Bo Yan, Gang Su arXiv:1406.0261 http://arxiv.org/abs/1406.0261 Abstract: The anisotropic geometric, electronic, and thermoelectric (TE) properties of bulk black phosphorus (BP) with strain applied along three lattice directions have been systematically investigated using first-principles calculations combined with semi-classical Boltzmann transport theory. The lattice constant b always increase whatever compressive or tensile strain is applied along z direction, showing an unusual mechanical response with a transition between positive and negative Poisson’s ratio, which may due to the hinge-like structure of BP. The electronic properties are sensitive to strain that there exist transitions of band gap among direct, indirect and zero with strain varying from compressive to tensile. For the TE performance of BP, when there is no strain applied, the ZT value is found to be maximal along x direction as 0.722 at 800K with an electron (n-type) doping concentration of 6.005×10cm, while being smaller for hole (p-type) doping or along other directions, indicating a distinctly anisotropic TE performance. Furthermore, the greatest enhanced ZT values could be obtained for electron (n-type) doped BP as 0.866 at 800K with a tensile strain of 7% applied along y direction. 34. Electronic Structures of Black Phosphorus Studied by Angleresolved Photoemission Spectroscopy