Low Temperature Deposition and Characterization of N- and P-Type Silicon Carbide Thin Films and Associated Ohmic and Schottky Contacts
Semiannual technical rept. 1 Jan-30 Jun 1994
NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
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Monocrystalline silicon carbide SiC films have been grown on vicinal 6H-SiC 0001 substrates via gas source molecular beam epitaxy at 1050- 1250 deg C. Using transmission electron microscopy, step bunching was observed at the outset of the initial stage of growth using C3H4Si2H6 ratios of 1,2 or 10. Subsequent growth occurred via island formation C2H4-rich or step-flow 11 ratio. Occurrence of the different growth modes may be controlled by changes in the surface diffusion length caused by surface reconstruction as a result of changing the CSi ratio. Cubic beta-SiC and hexagonal 6H-SiC deposit using high and 11 CSi ratios, respectively. Unintentionally doped films are n- type with n 0.2-1.0 x 10exp 17cu cm. Similar atomic and hole concentration of 5 x 10exp 18 and 1.2 x 10 exp 18, respectively, were measured in Al-doped p-type films. AlN deposited on 6H-SiC 0001 substrates possess a negative electron affinity. The surface Fermi level of the AlN is approx. 3.5 eV above the valence band maximum. Thin film electrical contacts of Co exhibited rectifying behavior with n 1.06 and a leakage current of 2.0 x 10exp -8 at -10 V. After annealing at 1000 deg C for 2 min, ohmic-like behavior was observed as a result of significant interface reaction.
- Inorganic Chemistry
- Electricity and Magnetism
- Solid State Physics