Development of a new MBE growth method for fabrication of high quality, double epitaxial Si/γ-Al 2O 3/Si structures

Abstract

The growth of Si on MgAl 2O 4/Si by conventional MBE technique was accomplished at growth temperatures ( T s) above 800°C. However, a large amount of auto-doping, equivalent to that by the CVD growth method, was caused by the stimulative reaction of Si with MgAl 2O 4 under an ultrahigh vacuum, even though T s was 150°C lower than that for CVD growth. This paper reports on a new MBE method to grow Si epi-film on restructured γ-Al 2O 3/Si at a T s of 700°C so as to minimize the auto-doping of Mg, Al and O atoms. The constitutional transformation from MgAl 2O 4 to γ-Al 2O 3 occured due to the depletion of Mg atoms caused by the reaction of Si beams with MgAl 2O 4. At a substrate temperature of 820°C, Mg atoms were effectively depleted throughout the entire region of 1000 Å thick MgAl 2O 4 layer under conditions in which flux density and total flux of the Si beams were 1×10 15 atoms/cm 2·s and 1.5×10 17 atoms/cm 2, respectively. The electron Hall mobility of the Si epi-film grown by the new MBE method is about 1060 cm 2/V·s, which is twice as large as that obtained for conventional MBE growth of Si on MgAl 2O 4 at 850°C.