Accession Number:

ADA214096

Title:

Group II Cubic Fluorides as Dielectrics for III-V Compound Semiconductors

Descriptive Note:

Final rept. Jun 1986-May 1989

Corporate Author:

PRINCETON UNIV NJ DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE

Personal Author(s):

Report Date:

1989-09-01

Pagination or Media Count:

9.0

Abstract:

The epitaxial growth of lattice matched CaxSr1-xF2Gallium Arsenide and GaAsCaxSr1-xF2 heterojunctions by molecular beam epitaxy is investigated. These heterojunctions are potential candidates for realizing opto- electronic devices involving III-V Compound Semiconductors. The composition x0. 5 is chosen to minimize the lattice mismatch at room and growth temperatures. The fabrication of the layers involves the sequential growth of GaAs wafers of a GaAs buffer layer, a 2000-3000A Ca5SrF3 layer, and a top 500-3000A GaAs layer. The growth along the 100, 111, 511 and 711 orientations is investigated. Optimum growth temperatures range from 500 C to 550 C for the fluorides, and 550 C to 600 C for the GaAs. The orientation of the substrate is conserved throughout the three epitaxial layers. The bulk crystallinity, studied with ion scattering, is found to be excellent in the GaAs buffer layer, fair to good in the fluoride layer, and poor to fair in the top GaAs layer. The high Miller- index GaAs surfaces 511, 711 exhibit a regular stepped structure 100 terraces which contributes to the reduction of anti-phase disorder in the fluoride layer. It is also found that the 511 orientation is favorable for the growth of the top GaAs layer. Rough morphology and facetting at fluoride surfaces are identified as the main problems for the growth of high quality top GaAs layers. Post-growth thermal treatments and electron-beam exposure will be investigated as potential solutions. Keywords Semiconductorinsulator semiconductor heterojunctions Calcium compounds Strontium compounds Fluorides.

Subject Categories:

  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE