Accession Number:

ADA244000

Title:

Growth, Characterization and Device Development in Monocrystalline Diamond Films

Descriptive Note:

Annual letter rept. 1 Jan-31 Dec 91,

Corporate Author:

NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s):

Report Date:

1991-12-01

Pagination or Media Count:

65.0

Abstract:

The nucleation of diamond grains on unscratched silicon wafer is enhanced by four order of magnitude relative to scratched substrates by using negative bias enhanced microwave plasma CVD in a 2 methanehydrogen plasma for an initial period. In vacuo surface analysis has revealed that the actual nucleation occurs on the amorphous C coating present on the thin SiC layer which forms as the product of the initial reaction with the Si surface. It is believed that the C forms critical clusters which are favorable for diamond nucleation. Similar enhancement was observed together with the occurrence of textured diamond films in the use of bias pretreatment of cubic Beta SiC substrates. Approximately 50 of the initial diamond nuclei were aligned with the SiC substrate. In contrast, the use of the biasing pretreatment for one hour on polycrystalline substrates resulted in only about 7 coverage with diamond particles. Numerous techniques have been used to analyze the nucleation and growth phenomena, especially micro Raman and scanning tunneling microscopy. The latter technique has shown that the morphology of doped and undoped diamond nuclei are similar, as well as the fact that significant concentrations of vacancy related defects are present. In device related-studies, uv-photoemission studies have shown that TiC occurs at the Ti-diamond 100 interface after a 400 C anneal. The Schottky barrier height from this metal on p-type diamond was determined to be 1.0 eV. Indications of negative electron affinity NEA was observed and attributed to emission of electrons that are quasi-thermalized to the bottom of the conduction band.

Subject Categories:

  • Electrical and Electronic Equipment
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE