Thermal decomposition pathway of Ge and Si oxides: observation of a distinct difference

In this paper, we report a comparison of the thermal decomposition pathways of ultrathin oxide layers, formed on Ge(100) and Si(100) surfaces, as reve aled by photoemission studies, employing synchrotron radiation. The oxide l ayer, in both the cases, consists of a mixture of, mainly, monoxide and dio xide species. On annealing, both the oxides undergo thermal decomposition a nd the desorbing species is the corresponding monoxide. However, we find th at their decomposition pathways are entirely different. On annealing the Ge oxide layer, the GeO2 species transforms to GeO on the surface and finally desorbs from the surface at similar to 425 degrees C. In contrast, anneali ng results in the transformation of SiO to SiO2 up to a temperature, lower than the desorption temperature (similar to 760 degrees C). At higher tempe ratures, SiO2 possibly transforms back to SiO and subsequently desorbs. The se phenomena may be related to the interface properties, since the thermody namic properties of individual oxides predict an opposite trend in their th ermal stability. (C) 2000 Elsevier Science S.A. All rights reserved.