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Relaxation and field-cycling nuclear magnetic resonance studies of doped III-V semiconductors.

Walsh, Kevin Anthony Peter. (1992) Relaxation and field-cycling nuclear magnetic resonance studies of doped III-V semiconductors. Doctoral thesis, University of Surrey (United Kingdom)..

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Nuclear Magnetic Resonance Field Cycling has been further developed as a spectroscopy for impurities in III-V semiconductors. It has been used to investigate the quadrupolar and hyperfine interactions around impurity sites in GaAs and InP. Large low field relaxation peaks in the range 0 to 100 Gauss have been observed in matrix nuclei resulting from deep level impurities and broader peaks up to 1000 Gauss from shallow level impurities. The temperature dependences, from 4K to 300K, of the spin-lattice relaxation times of the matrix nuclei in doped III-V semiconductors have been measured and interpreted in terms of Korringa and quadrupolar relaxation. A detailed theory of the field-cycling experiments based on the cross-coupling of energy levels of the matrix nuclei has been developed. In addition, the spin-lattice relaxation rates have been used to understand the dynamics of cross-coupling. Anomalous field-cycling spectra have been observed in optically irradiated InP:Co and low frequency (<1MHz) irradiated InP:S. These have been investigated in depth and possible models to interpret the results have been developed. Finally, a system has been designed and constructed to investigate NMR and related phenomena in two-dimensional electron gas systems.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Walsh, Kevin Anthony Peter.
Date : 1992
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:15
Last Modified : 15 Mar 2018 19:02

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