Growth of Si on different GaAs surfaces: A comparative study

We studied the chemical bonding at the interface between Si and GaAs by synchrotron radiation photoelectron spectroscopy. Thin Si films were deposited at 450 degrees C or 500 degrees C on different GaAs substrates: the As-rich GaAs(100) and GaAs(111)B surfaces as well as the Ga-rich GaAs(100) and GaAs(111)A surfaces. In this paper we compare the properties of these four interfaces. On As-rich GaAs the Si bonds solely to As. No Ga-Si bonds are formed. The Si atoms occupy the equivalent of next-layer Ga sites. Neither As nor Ga segregation to the surface of the Si film is observed. On the Ga-rich GaAs(100)-(4x2) and GaAs(111)A surfaces Ga-Si bonds are formed at the interface. Arsenic segregates to the surface of the Si film, leaving As vacancies behind at the interface. While these results can be understood in terms of simple models, the behavior of the As-rich GaAs(111)B surface is more complicated. We discuss this surface in detail.