Band gap engineering using the LDA-1/2 method to calculate excited states in materials: study of quantum confined systems

• Grant number: 12/14617-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2012
• End date: February 28, 2014
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Lara Kühl Teles
• Grantee: Mauro Fernando Soares Ribeiro Junior
• Host Institution: Divisão de Ciências Fundamentais (IEF). Instituto Tecnológico de Aeronáutica (ITA). São José dos Campos , SP, Brazil

Abstract

The theoretical method to calculate excitations in solids called LDA (or GGA)-1/2, was developed by the professor Luiz Guimarães Ferreira, from the University of São Paulo, in collaboration with the Group for New Materials and Nanostructures - GMSN. The LDA(GGA)-1/2 method has achieved progressive successes in the description of semiconducting systems, interfaces, magnetic materials, semiconducting interfaces alloys and magnetic alloys. The greatest advantages of the method are: simplicity in the implementation, low computational cost (time and memory), precision in band gap calculations comparable to the state-of-the-art GW method, being free of adjustable parameters. In particular, the candidate's PhD thesis was entirely developed with use of this method under Prof. L. G. Ferreira's supervision. There are, however, some immediate challenges to the LDA-1/2 method, as the calculation of total energies and quantum confined systems, as 2D systems, e.g. ultrathin films of a few atomic layers, and 1D systems as quantum wires. In this project, our main objective is to focus the second issue with the LDA-1/2 method, giving sequence to the validation of the method to calculate correctly the excited states of the myriad of systems elsewhere in condensed matter. This general objective involves the theoretical development of how to treat the quantum confinement effects with LDA-1/2, as well as its application to systems of interest that present such effects. In particular, we shall study heterostructures of one InN monolayer embedded in GaN matrix, as (GaN)n/(InN)1/(GaN)n, as part of the development of high efficiency solar cells. The 1D systems will be semiconductor nanowires, e.g. ZnO and Si. After our preliminary results already obtained with the new method, we believe that this is an excellent moment to advance in the theoretical study of nanosystems, given the excellent theoretical and experimental support they have been attracted in the last years. (AU)

Scientific publications

(4)

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

MATUSALEM, FILIPE; RIBEIRO, JR., MAURO; MARQUES, MARCELO; PELA, RONALDO R.; FERREIRA, LUIZ G.; TELES, LARA K.. Combined LDA and LDA-1/2 method to obtain defect formation energies in large silicon supercells. Physical Review B, v. 88, n. 22, DEC 10 2013. (12/14617-7)

RIBEIRO, JR., M.; MARQUES, M.. Theoretical study of InN/GaN short period superlattices to mimic disordered alloys. Journal of Applied Physics, v. 115, n. 22, JUN 14 2014. (12/14617-7)

MATUSALEM, FILIPE; RIBEIRO, MAURO, JR.; MARQUES, MARCELO; PELA, RONALDO R.; FERREIRA, LUIZ G.; TELES, LARA K.. Combined LDA and LDA-1/2 method to obtain defect formation energies in large silicon supercells. PHYSICAL REVIEW B, v. 88, n. 22, p. 7-pg., 2013-12-10. (12/14617-7)

RIBEIRO, JR., MAURO. Application of the GGA-1/2 excited-state correction method to p-electron defective states: the special case of nitrogen-doped TiO2. CANADIAN JOURNAL OF PHYSICS, v. 93, n. 3, p. 261-266, MAR 2015. (12/14617-7)