Atomic Layer Epitaxy of Group IV Materials: Surface Processes, Thin Films, Devices and Their Characterization.
NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
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The ALE technique has been employed to deposit monocrystalline 3C-SiC thin films at 860 or - 10 deg C. Wafers containing heterojunction bipolar transistor structures have been completely processed and characterized. No transistor activity was detected in any of the HBT structures. Post growth oxidation anneals in argon followed or proceeded by oxygen environments improved both properties. However, the anneals in oxygen also resulted in the growth of a SiO2 layer at the silicon interface which reduced the capacitance of the structure. An expression for the optimum oxidation time, tau, was developed as a function of the initial thicknesses of the deposited film. The films have large MOS capacitance but also have larger leakage currents compared to those of epitaxial CeO2 films on Si111 substrates. However, improved leakage and breakdown characteristics were obtained with annealing in forming gas. The growth parameter, alpha, the ratio of the growth rates on 100 and 111 facets for diamond films deposited on Si and Ti by microwave plasma CVD has been studied using SEM micrographs. Different morphologies were generated on Si under different deposition conditions. The value of alpha increased with decreasing temperature and increasing methane concentration, as expected. A value of alpha for Ti was not obtained due to the heavily twinned particles.
- Solid State Physics