Accession Number:

ADA467664

Title:

Substrate/Oxide Interface Interaction in LaAlO3/Si Structures

Descriptive Note:

Conference paper

Corporate Author:

AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE

Personal Author(s):

Report Date:

2004-01-01

Pagination or Media Count:

7.0

Abstract:

Amorphous lanthanum aluminate films LaAlO3 were deposited on Si substrates at room temperature using rf sputtering in pure Ar or an ArO2 mixture with a stoichiometric target. The film composition was analyzed using XPS and EDX. The evolution of the material resulting from annealing at temperatures in excess of 900 degree C was studied using infrared spectroscopy, XPS profiling and AFM. We obtain clear evidence for in-diffusion of Si from the substrate into the dielectric film. FTIR analysis showed only one peak centered at 747 cm with an FWHM of 185cm for as-deposited samples indicating an amorphous structure. Annealed samples showed very narrow absorptions at 483-510, 607, 695-720 and 811 cm. No evidence for SiO2 peaks at 1060 cm was observed suggesting that the LaAlO3 structure tends not to reduce into a mixture of SiO2 and a silicide. Short time annealing at 1000 degrees C results in a broad band at 905 cm which can be interpreted in terms of the formation of a layer rich in Si-O-La bonds. Nitridation of the substrate before oxide deposition and annealing slows the degradation process but does not suppress it. X-ray diffraction analysis of the annealed films indicates a very oriented crystalline structure, yet unidentified, whose direction depends upon the orientation of the Si substrate. The dielectric constant in both annealed and as-deposited films was measured to be less than 14 and the leakage current density was very low. Some mobile charge was detected. This dielectric constant is substantially less than the value 25 anticipated from bulk, single crystal measurements.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry
  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE