Pulsed electrically and optically detected magnetic resonance spectroscopy of disordered semiconductors

Update Item Information
Publication Type dissertation
School or College College of Science
Department Physics & Astronomy
Author Lee, Sang-Yun
Title Pulsed electrically and optically detected magnetic resonance spectroscopy of disordered semiconductors
Date 2011-08
Description Electrically and Optically detected magnetic resonance (EDMR and ODMR) spectroscopy allows investigation of the microscopic nature of paramagnetic centers which influence the electrical or optoelectronic properties of semiconductors. Traditionally, EDMR and ODMR have been conducted as adiabatic magnetic field sweep spectroscopies under continuous wave (cw) application of electromagnetic fields. It is shown here that information about the dynamics of spin-dependent processes obtained from cwEDMR and cwODMR is determined by many electronic- and spin-relaxation parameters, which make the interpretation of experimental data quantitatively ambiguous. In contrast, it is shown that transient EDMR and ODMR experiments, so called pulsed (p)EDMR and pODMR, are significantly less ambiguous. For spin-dependent processes based on intermediate pairs of paramagnetic states, the cwEDMR and cwODMR as well as pEDMR and pODMR dynamics are derived analytically and the application of these results for the interpretation of experimental data is discussed for two examples: (i) The pEDMR study of spin-dependent recombination in silicon rich hydrogenated amorphous silicon nitride (a-SiNx:H) which showed the presence of a variety of mechanisms such as dangling bond recombination through weakly spin-coupled paramagnetic states but also recombination through band tail states which were strongly dipolar or exchange coupled. These processes had previously been observed in hydrogenated amorphous silicon (a-Si:H). However, while in a-Si:H, these processes took place solely as geminate recombination, they were of nongeminate nature in the a-SiNx:H. (ii) The pODMR study of excitonic recombination in a ?-conjugated polymer, namely, poly[2-methoxy-5-(20- ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). The presence of magnetic resonance induced spin-beat oscillations in the fluorescence intensity was confirmed. Based on the existing polaron-pair recombination model, previously pEDMR-detected beat signals seen here with pODMR in an identical manner. Two types of MEH-PPV, one fully hydrogenated and one partially deuterated were subjected to pODMR. The deuterated materials showed a different beat oscillation dependence of the driving field power pattern which was indicative of smaller hyperfine fields in the deuterated material.
Type Text
Publisher University of Utah
Subject Electrically detected magnetic resonance; Electron spin resonance; Magnetic resonance; MEH-PPV; Optically detected magnetic resonance; Silicon rich silicon nitride
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Rights Management Copyright © Sang-Yun Lee 2011
Format Medium application/pdf
Format Extent 3,653,513 bytes
Identifier us-etd3,53100
Source Original housed in Marriott Library Special Collections, QC3.5 2011 .L33
ARK ark:/87278/s6fn1mzg
Setname ir_etd
ID 194520
Reference URL https://collections.lib.utah.edu/ark:/87278/s6fn1mzg