Speaker
Description
Diamond-based compounds own a large band gap about the Fermi level making them ideal candidate materials to build nanoengineered devices with wide applicability in nanophotonics, optomechanics, photovoltaics and electronics. However, the band gap must be suitably tuned for each target application.
With this aim, we performed quantum mechanical simulations of diamond-based materials doped with a variety of doping atoms in different concentrations.[1] Subsequently, we expanded the study by considering cluster defects formed by dopants and carbon vacancies in different geometric configurations; such an expansion allowed us to focus on coupled structural-electronic features even in more detail. Furthermore, we were able to investigate more intriguing electronic structures with a variety of opto-electronic applications such as intermediate band photovoltaics or lasers. We conducted extensive electronic and geometric analysis on the ground state geometries, using geometric and electronic features such as interatomic distances, orbital polarizations, bond covalencies and Hirshfeld charges. We show that the specific charge distributions at the dopant atomic site govern the size of the band gap; in order to tune the gap and the band structure in general, we propose how to choose the suitable dopant atomic types, their concentration, geometric configuration and how to impose convenient axial strains on the structures. Furthermore, we suggest different routes of acting on the lattice parameters to switch the character of the band gap from indirect to direct.
The results of our investigation constitute guidelines for further use in experimental and technical fields and can be promptly applied to the design of new semiconducting materials. Furthermore, as our theoretical results are general, they can be applied to the study of optical and electronic materials irrespective of their chemical composition and atomic topology.
This work has been supported by the project “Center for Advanced Photovoltaics” [grant number CZ.02.1.01/0.0/0.0/15_003/0000464]; the Grant Agency of the Czech Technical University in Prague [grant number SGS22/166/OHK3/3T/13]; and by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ [grant number ID: 90140].
References
[1] A. Cammarata, M. Kaintz and T. Polcar, Diam. Relat. Mater., 2022, 128, 109237.
