Interaction of oxygen with a Ge-covered Si(100) surface

Abstract

The interaction of oxygen with a Ge-covered Si(100)×2 × 1 surface has been studied by means of Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS), thermal desorption and work function (WF) measurements. It has been found that the initial oxygen sticking coefficient of the Ge-covered (1 < θGe < 3) Si(100) is almost independent of the Ge coverage, θGe, and is close to that of a bare Si surface. Strong suppression of the oxygen uptake rate has been observed at 300 K for moderate oxygen coverages. This effect is weaker for the oxygen adsorption kinetics at 500 K. AES and EELS results show that short time annealing above 370 K can induce oxygen transfer from Ge to Si atoms. This is accompanied by diffusion of Si and formation of Si oxides over the Ge layer, as judged from the WF and AES data. The annealing experiments show that the shape of the GeO TPD curves is determined by complicated reduction-oxidation reactions in which diffusion of oxygen is involved.