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Atomic Layer Epitaxy of Group IV Materials: Surface Processes, Thin Films, Devices and Their Characterization.
Semiannual Technical rept. 1 Jul-31 Dec 94,
NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
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Residual surface contaminants were removed from vicinal 6H-SiC0001 surfaces in UHV via high temperature annealing in SiH4. Characterization via AES, EELS, LEED, XPS, and UPS was conducted. At T850 deg C, the surface oxide was rapidly removed. Exposure to approx. 400 Langmuir 10exp-6 Torrdotliters of SiH4 resulted in complete surface oxide removal and a nearly stoichiometric l x l 6H-SiC surface suitable for ALE of SiC. Further exposure resulted in a 3 x 3R30 deg Si-rich reconstructed surface. Subsequent annealing in UHV resulted in a square root of 3 x square root of 3R30 deg Si deficientgraphitic reconstructed surface. The first set of wafers containing HBT device structures were fabricated on SiC films grown via ALE. No transistor activity was detected. Electrical characterization and SEM showed the most likely fault to be inaccurate etching of the SiC emitter. Nucleation and growth of oriented diamond particles on seeded, 0001 oriented single crystal Co substrates was achieved via multi-step, hot-filament CVD process involving seeding, annealing, nucleation and growth. Diamond particles oriented 111 were obtained. Micro-Raman showed a FWHM of 4.3cm. A very weak graphitic peak was observed on regions of the substrate not covered by the diamond particles. A nucleation model has been proposed. Initial results showed that CeO2 film grows epitaxially on 111 Si substrates. The CeO2 films had density of interfacial traps and fixed oxide charge values comparable to that of amorphous SiO2Si.
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