Growth of ternary alloy Si1−<i>x</i>−<i>y</i>Ge<i>x</i>C<i>y</i> by rapid thermal chemical vapor deposition

Abstract

Epitaxial layers of the ternary alloy SiGeC were grown on 〈100〉 Si substrates. Using a rapid thermal chemical vapor deposition reactor working at low temperature and reduced pressure (550 °C and 1 Torr), we obtained SiGeC layers with a carbon concentration into substitutional sites of up to 1.5%. We used two methods to measure the substitutional C fraction in the SiGeC samples: Fourier transform infrared measurements at room temperature and x-ray diffraction of the d004 atomic distance in the alloys. Using methylsilane (SiH3CH3 or MS) as the carbon precursor, we measured an activation energy for Si0.845Ge0.15C0.005 growth of around 52 kcal/mol and showed that C incorporation into substitutional sites saturates at high MS flows. Finally, thermal annealing of these ternary alloys has been studied: a 800 °C annealing for 15 min leads to oxygen and carbon diffusion, whereas strain relaxation occurs by amorphous SiC precipitation with a 900 °C, 15 min annealing.