טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentEkaterina Dikarov
SubjectPulsed Electron Spin Resonance Imaging Study of Paramagnetic
Centers in the Solid Phase
DepartmentDepartment of Physics
Supervisors Full Professor Keren Amit
Professor Blank Aharon
Full Thesis textFull thesis text - English Version


Abstract

Electron spin resonance (ESR) spectroscopy has been used for over 6 0 years to study a variety of paramagnetic species. Being a powerful analytical tool it has many applications in chemistry, biology and physics, many of them involving solid- state samples.  For example, ESR spectroscopy is a leading method in the analysis of crystal point defect in general and specifically of semiconductor paramagnetic defects.

            Despite this success, there are still several major issues that limit the applicability of ESR to these types of applications: ESR is relatively insensitive spectroscopic method, often requiring many billions of spins to obtain measurable signal.  Furthermore, when inhomogeneous samples are considered, ESR image resolution is often too poor (many microns) to be sufficient for many solid state and semiconductor-related applications.

            This work makes use of a new pulsed ESR imaging system with improved sensitivity and image resolution. This new "home-made" system was used to obtain images of solid LiPc crystals with resolution of 1.1×0.95×12.5 µm3 and sensitivity of ~1.3×109 spins per voxel. 2D images of N@C60:C60 powder inside photolithographicly pre-made features with image resolution of 4×5.7 µm2 are also presented in this work. And finally we introduce here the first application for detection of point defects (E’ centers) diffusion in SiO2 (quartz).