Mecanismos de crescimento e propriedades elétricas de nanofios de InGaAs e GaAs

Abstract

This work presents the experimental and theoretical results obtained from the analysis of the growth of nanowires ternary allo InGaAs, with mole fractions of 5, 10, 15 and 20 % of InAs and characterization of properties electrical nanowires p-type GaAs doped with magnesium and silicon. The work is divided into six chapters. In chapter 1 we will do a little review of the electronic properties, mechanisms of doping p-type and n-type, Raman scattering and growth mechanisms of the nanowires used in this work. Chapter 2 will discuss also briefly the experimental techniques used for the growth and characterization of nanowires. The Chapter 3 deals with the morphological characterization and structural properties of nanowires InGaAs. The chapter 4 is dedicated to electrical characterization of nanowires of GaAs doped with Mg. Chapter 4 will show the main results of the electrical characterization of nanowires of GaAs doped with Si. The Chapter 6 is devoted to the study of doping with Si nanowires via the Raman spectroscopy in transmission geometry. The nanowires were grown by molecular beam epitaxy technique (MBE) on GaAs (111) B, InAs (111)B and Si(111) substrates using nano-colloidal particles of gold (Au) as catalysts. All morphological data, chemical composition, crystal structure and electrical properties of the nanowires were obtained using the scanning electron microscopy techniques (SEM), Raman spectroscopy, diffraction X-ray, resistivity measurements, and temperature dependence of current-voltage curves. Through SEM it was possible to establish the radius dependence of the nanowire growth rate, and thus, understanding the growth mechanisms of the nanowires. Measurements of X-ray allowed to analyze the chemical composition of each sample. The analysis of the dependence of the electrical properties with temperature shows that the high temperature region (above room temperature), the electron transport is limited to the driving of free holes in the valence band, however in the region of low temperature driving is determined by hops between impurities in the energy region of the semiconductor forbidden. Three driving mechanisms heels have been identified and studied. With the purpose of comparing and understanding the amphoteric nature of silicon in the doped GaAs nanowires were made measurements of the concentration and mobility using the technique Raman spectroscopic transmission, and the results of analysis are shown in the end section of work.