Regensburg 2004 – wissenschaftliches Programm
O 5.7: Vortrag
Montag, 8. März 2004, 12:45–13:00, H44
STM Studies of ultrathin SixGe1−x films grown on Si(111) by Chemical Vapour Deposition — •Selvi Gopalakrishnan, H. Rauscher, and R.J. Behm — Abt. Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm
The influence of terrace width, temperature and gas composition on the morphology and composition of epitaxial SixGe1−x films grown on Si(111) by chemical vapour deposition (CVD) was investigated by STM and XPS. Si2H6 and GeH4 were used as the precursor gases. Investigations were carried out with two different GeH4:Si2H6 gas ratios, (a) a 7:3 ratio with an effective Ge:Si ratio of about 1:1 and (b) a 9:1 ratio where the effective ratio of Ge:Si is about 4:1. SiGe layers were deposited at a constant pressure of 2.5×10−6 mbar on wafers with two different terrace widths (average terrace widths of 2000 A and up to 6000 A) and at deposition temperatures of 750 K and 850 K. At 750 K, hydrogen is completely desorbed from the Ge surface and at 850 K the rate of hydrogen desorption from the Si surface is a maximum. The large terrace widths allow the study of the SiGe CVD process, in particular the nucleation behaviour, at low pressures and higher temperatures and derive data on the mobility of the mobile Si and Ge containing species.