CARACTERIZAÇÃO DE DEFEITOS MECÂNICOS PRODUZIDOS POR NANOINDENTAÇÃO NO INP / CHARACTERIZATION OF MECHANICAL DEFECTS PRODUCED BY NANOINDENTATION IN INP

AUTOR(ES)

CLARA MUNIZ DA SILVA DE ALMEIDA

DATA DE PUBLICAÇÃO

2009

RESUMO

In this thesis, the mechanical deformation mechanism of semiconductors III-V was studied, especially for InP. Defects were produced by indentations using an atomic force microscope and a Triboscope nanoindenter. The AFM tip torsion during indentation difficult the control and the reproducibility of AFM nanoindentation experiments. Nevertheless, the tip torsion allowed the measurement of the materials Yield stress. A study of the mechanical deformation mechanism of the native oxide that is presented in the surface of InP (100) and GaAs (100) was done. The residual plastic impressions attributed to native oxides were observed on the semiconductors surface. The plastic deformation process of the InP was studied in nanoindentation experiments using a Berkovich and a conosferical tip. The InP deformation mechanism observed with a Berkovich tip presents discontinuities for indentations performed at high loads, that are associated with successive slip of {111} planes along the <110>directions. The pressure distribution on the indented region, applied by the conosferical tip, is isotropic allowing a better visualization of the elastic/plastic transition in a material deformation process. The plastic deformation of InP using this tip is initialized with a catastrophic event, that appears in the indentation curves as a discontinuity. Small cracks were observed around the indentations using both tips, suggesting that some dislocations loops ends on the InP surface. Bigger cracks were observed in indentations with the conosferical tip and they were attributed to material fracture produced by the locking of dislocations near the surface. Transmission electron microscopy was done in the nanoindentation cross section showing a high density of defects created by the slip of the {111} planes.

ASSUNTO(S)

microscopia de forca atomica atomic force microscopy physics fisica

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