UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2015 Meeting


Section: Solid State Physics and Materials Science


Title:
Optoelectronic properties in low-dimensional systems: BN-graphene coreshell nanoflakes, GaN-AlN core-shell nanowires and PbI2 nanostructures (nanowires and slabs)


Authors:
Andreea-Alexandra NILA (1), G. A. NEMNES (1), A. MANOLESCU (2)


Affiliation:
1) University of Bucharest, Faculty of Physics, Materials and Devices for Electronics and Optoelectronics Research Center, Magurele, Ilfov, Romania

2) School of Science and Engineering, Reykjavik University, Reykjavik, Iceland


E-mail
andreea.nila@gmail.com


Keywords:
BN-graphene nanoflakes, GaN-AlN nanowires, PbI2 nanostructures, density-functional theory


Abstract:
The electrical and optical properties of different nanostructures are investigated using first-principle calculations based on density-functional theory. Due to a different spatial confinement of the carriers, it is found that the properties can be tuned by using different sizes and proportions of the core-shell materials. One observes a modification of the electrical properties as follows: a) a gap opening by adjusting the core-shell ratios of nanostructures involved; b) a band gap of the PbI2 nanowires that vary significantly by changing the diameter, with a metallic behaviour for the small-radius structures; and c) an increase of the band gap of the slabs with decreasing the widths. In addition, we pointed out anisotropic properties of the nanoflakes by modifying the orientation of the optical vector, with the absorption coefficient enhanced when the optical field is oriented perpendicular with respect to the c-crystallographic axis. In the case of GaN-AlN nanowires, an induced phase transition from wurtzite (WZ) to a graphite-like (GL) phase, upon applying an external axial pressure, introduces sharp peaks in the absorption coefficient, which can be correlated with the complex dielectric function of the applied stress for the core-shell nanowires.


References:

1. M. Ethayaraja et al., J. Phys. Chem. C 111, 3246-3252 (2007);

2. L. Ci et al., Nat. Mater. 9, 430-435 (2010);

3. P. Rani et al., Physica E 62, 28-35 (2014);

4. J. Tang et al., Nat. Nanotehnol. 6, 568-572 (2011);

5. B. Daudin et al., Phys. Procedia 28, 5-16 (2012);



Acknowledgement:
Support of the EEA Financial Mechanism 2009-2014 staff mobility grant and the hospitality of Reykjavik Univesity.