Characterization of Si/CoSi2/Si(111) heterostructures using Auger plasmon losses
Abstract
The cobalt LMM Auger spectra are observed to undergo significant shape changes as a function of Si overlayer thickness and annealing temperature in Si/CoSi2 /Si heterostructures prepared by codeposition and solid phase epitaxy on Si(111) substrates. The changes are dominated by strong increases of the bulk plasmon loss intensity and shifts in the plasmon loss energy with increasing Si overlayer thickness. These effects can be used to probe the overlayers with electrons generated in the underlying layers. They are used here to measure the thickness of Si overlayers on CoSi2 . We find a linear relationship between the ratio of the plasmon loss peak associated with the Co-L23 VV Auger peak to the Auger peak itself and the known thickness of deposited Si overlayers for thicknesses up to 30 Å. Using this calibration, we monitor island formation in annealed Si/CoSi2 /Si and diffusion of Si in CoSi2 /Si. We deduce the formation of islands in the deposited Si overlayers at temperatures of 550 °C for thicknesses less than 30 Å. We observe Si diffusion in CoSi2 /Si at temperatures as low as 400 °C. We measure activation energies of 0.52-0.60 eV for the diffusion, as determined from Arhennius plots of the plasmon/Auger data, and conclude that the diffusion most likely proceeds through residual defects in the CoSi2 .
- Publication:
-
Journal of Applied Physics
- Pub Date:
- May 1989
- DOI:
- 10.1063/1.342627
- Bibcode:
- 1989JAP....65.3531S
- Keywords:
-
- Auger Spectroscopy;
- Cobalt Compounds;
- Heterojunction Devices;
- Plasmons;
- Silicon Films;
- Annealing;
- Electron Energy;
- Energy Dissipation;
- Molecular Beam Epitaxy;
- Molecular Diffusion;
- Solid-State Physics