Influence of Various Impacts on the Composition and Structure of the Surface of Single-Crystal Si

Using the methods of Auger-electron spectroscopy, scanning electron microscopy, reflection high-energy electron diffraction and low-energy electron diffraction, the influence of high vacuum on the composition and structure of the surface of Si single crystals purified at a pressure in the vacuum chamber of P ≈ 10–7 Pa by various methods is studied. The methods are: annealing and ion-plasma treatment of Si and annealing after preliminary implantation of Ba+ ions. It is shown that, regardless of the purification conditions, the exposure of Si(111) in a vacuum chamber with a residual pressure within the range 10–5–10–7 Pa leads to the appearance of oxygen and carbon atoms on its surface, the concentrations of which depend on the pressure of the residual gas in the device and the holding time. At R ≤ 10–6 Pa, the total concentration of O and C do not exceed 0.5–0.7 at % and they are easily removed by short-term annealing at T = 1000 K. The exposure of Si in a vacuum chamber to a residual pressure of 10–5 Pa leads to an increase in the surface concentration of O to ~0.8 at %, and C up to 0.2 at %. Based on these data, it can be concluded that surface contamination mainly occurs due to the adsorption of oxygen atoms (molecules) from the residual gas in the device.

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