Residual lattice disorder in Gallium Arsenide due to neutron transmutation doping /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The production of lattice disorder in high-purity undoped, semi-insulating Czochralski-grown GaAs due to neutron transmutation doping has been investigated by single- and double-alignment Rutherford backscattering and channeling measurements of 120-keV protons incident on <100> GaAs. The measured critical half-angle for the <100> single-alignment measurements was 1.34°[plus or minus]0.05°, and the observed minimum yield was 0.045. The double-alignment minimum yields obtained by aligning the detector with the <110> and <111> axes were 0.0046 and 0.0102, respectively. GaAs samples were irradiated for 100 and 300 hours with a thermal neutron flux density of approximately 1.8 x 10^13 n/cm^2-sec and a fast neutron flux density of about 4.6 x 10^12 n/cm^2-sec. The measured residual lattice disorder agreed reasonably well with the predicted displacement concentrations and was observed to be approximately uniform to a depth of 2000 A. In addition, the lattice disorder appeared to consist primarily of randomly displaced point defects. In situ isochronal annealing of the GaAs samples was performed for 30 minutes at temperatures up to 550°C. No encapsulant or cover was utilized during the annealing procedure. The single- and double-alignment spectra for the neutron-irradiated GaAs samples which were annealed for 30 minutes at 550°C matched the spectra obtained from a nonirradiated sample within the 8% error attributable to reproducibility. The activation energy for lattice recovery of GaAs samples irradiated for 300 hours was estimated to be 0.06 eV for annealing temperatures below 350°C. For annealing temperatures above 350°C, the observed results were consistent with a published activation energy of 0.3 eV. Finally, the average number of displacements produced by 120-keV protons incident along the <100> aligned direction and random-equivalent direction in GaAs were determined to be 0.35 displaced atoms/proton and 1.3 displaced atoms/proton, respectively. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Nuclear engineering." |
| Physical Description: | xiii, 116 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |