Quantum Plasmonics of Few Electrons in Strongly Confined Doped Semiconducting Oxide Nanocrystal: A DFT+U Study of ZnGaO

Photodoping experiments by Faucheaux and Jain [1] show that electrons as few as 4 to 5 may sustain localized surface plasmonic oscillations in a nanocrystal. Gamelin et al [2] also claim that about as low as 3 electrons in nanocrystal are in involved in their photodoping experiment. Theoretical explanation by Jain [3] is based on free conduction electrons confined to a potential well to get qualitative results. On the other hand, Gamelin et al [2] used a semiclassical approach that involves quantum corrections to explain their results. In this talk, we present our DFT+U results of ZnO doped by Ga to find out if plasmonic oscillation are indeed sustained with 3, 4, 5, or 6 electrons in a spherical nanocrystal of 1.4 nm in diameter. We optimized the bulk unit cell to get a band gap of 3.37 eV and built the supercell from the optimized unit cell. Following geometric optimization of the supercell, optical calculations were performed in the independent particle approximation (IPA) as implemented in VASP code. The doping by Ga instead of the often-used Al to dope ZnO is to minimize local effects to justify IPA. Results of extinction and absorptions calculations will be presented.    

 

[1] J. A. Faucheaux and P. K. Jain, J. Phys. Chem. Lett. 4, 3024 (2013)

[2] A. M. Schimpf, N. Thakkar, C. E. Gunthardt, D. Massiello, and D. R. Gamelin, ACS Nano 8, 1065 (2014)

[3] P. K. Jain, J. Phys. Chem. Lett. 5, 3112 (2014)