Electron spectroscopy of porous silicon layers. Indirect detection of hydrogen by elastic peak electron spectroscopy

Abstract

Efficient visible luminescence from porous Si (PSI) layers is associated with the quantum size and the presence of hydrogen as a passivaant on the inner surface. The increase of the amount of H was performed by wet chemical etching in HF, producing the increase of photoluminescence intensity. The detection of H is not possible by AES or XPS and is difficult even with EELS. Elastic peak electron spectroscopy (EPES) showed a large decrease of the elastic reflection coefficient Y, appearing in the elastic peak, and measured with a retarding field analyser (RFA). The effective elastic backscattering coefficients of a monolayer of H, Si, 0 were calculated for the RFA angular window and resulted in reasonable agreement with literature data available. They were completed for the 50-100 eV range. Experiments on a Si(ll1) wafer verified calculations. A dramatic decrease of re was found on HF-etched Psi (a factor of 3-10) in the 50-100 eV range. Above 200 eV, effects are shadowed by the contribution of deeper layers of the substrate and reduced attenuation of the H adlayer. This indicates the formation of high H coverage on the porous inner surface. Experiments are interpreted by multiple elastic reflection and attenuation of electrons by the H-covered porous surface. Detailed AES and EELS studies made with a hemispherical analyser resulted in Si and SiO, bond on the surface.

Surface Analysis: X-ray Photoelectron Spectroscopy and Auger Electron Spectroscopy

“…From about 1970 to the present time, these techniques have grown in acceptance by the scientific community. Much of this activity has been documented in earlier Fundamental and Application Reviews in Analytical Chemistry ( − ).…”

Experimental and model study of the Rh/Al system by means of EPES

“…2 -5 Evaluation of IMFP is based on the comparison of the measured elastic backscattering intensity with calculated intensities found by the Monte Carlo (MC) simulation of electron trajectories in the solid. EPES has also been used for: studies of systems consisting of an overlayer deposited on a substrate; 6,7 hydrogen detection on the surface; 8 surface composition of alloys; 9 examining growth modes of ultrathin gold films deposited on nickel 10 or on Al and alumina; 11 and the studies of surfaces with overlayers. 12,13 It has been shown that there is good accordance between experimentally obtained parameters describing elastic backscattering and theoretical predictions.…”