Optical and electronic characterizations of semiconductor films using transmittance and reflectance spectra

• Grant number: 12/20445-4
• Support type: Scholarships in Brazil - Master
• Effective date (Start): May 01, 2013
• Effective date (End): April 30, 2015
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Jose Humberto Dias da Silva
• Grantee: Carlos Guilherme Gonçalves de Azevedo
• Home Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

Some existing methods for determination of optical parameters of semiconductor films allow the determination of the refractive index, absorption coefficient, and thickness of thin films. However these methods are often limited by approximations.In this dissertation the development of a precise method for calculating the optical constants of semiconductor thin films from transmittance and reflectance spectra is proposed. Complete transmittance and reflectance expressions, derived directly from Maxwell's equations will be used in the calculations. The developed programs will take into account the coherent multiple reflections in the films and incoherent multiple reflections in the substrate. When applying the method to homogeneous films with plane and parallel faces, the aim is to get accuracy of the order of 1%. The transmittance and reflectance measurements will be performed in the 200 nm to 3300 nm range, using a Perkin-Elmer L1050 spectrophotometer equipped with integrating sphere. The calculation method will be based on fitting procedures of the optical constants in the region of interference fringes of the spectrum, and on an iterative calculation for the high absorption range. The calculated optical absorption coefficient will be used to determine the optical bandgap of the material of interest. The interpretation of results will be based on the semi-classical interpretation of the absorption coefficient, in which the electronic transitions between occupied and unoccupied levels are related with the dissipation of an electromagnetic wave.The method will be initially applied to the determination of the optical parameters of GaSe films deposited by thermal evaporation, and GaN, TiO2 and CoO films produced in our laboratory by reactive sputtering.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

AZEVEDO, Carlos Guilherme Gonçalves de. Caracterização óptica e eletrônica de filmes semicondutores usando espectros de transmitância e refletância. 2015. 131 f. Master's Dissertation - Universidade Estadual Paulista "Júlio de Mesquita Filho" Faculdade de Ciências..