Interdisciplinary surface studies on porous Si(PSi)—I. Elastic peak electron spectroscopy (EPES), valence band XPS and atomic force microscopy (AFM)
Abstract
The paper deals with porous Si (PSi) samples, prepared with different parameters (substrate, current density, solution, etc.) of anodization and anodic oxidation. The porosity of samples varied between 36 and 78%, their thickness was 1-5 p.m. The samples were studied in six laboratories using complementary methods. The spectra of elastic reflection coefficients r e(E p) are characteristic of the composition and they are affected by the structure of the surface layer. They were measured with a retarding field analyser using spectrometer correction and deduced from the elastic peak versus E p primary energy. The r e(E p) showed a dramatic decrease in the 50-100 eV range with H adatoms on the surface, produced by HF treatment. It is caused by attenuation and multiple elastic reflections of electrons on the porous surface with H adatoms. An oxidized sample showed a contrary effect, which can be explained by the elastic reflection cross-sections of Si and O in this low energy range. Valence band XPS spectra were measured with a KRATOS XSAM 800 analyser. They showed changes with HF treatment and porous structure. To avoid difficulties with STM due to the oxide, the surface topography was mapped by atomic force microscopy, resulting in 0.3-0.9 nm roughness on samples of 36% porosity.
- Publication:
-
Vacuum
- Pub Date:
- January 1995
- DOI:
- 10.1016/0042-207X(94)00114-6
- Bibcode:
- 1995Vacuu..46..493G