Low-temperature epitaxial growth of high quality Si1−xGex (x ≥ 0.99) films on Si(001) wafer by reactive thermal chemical vapor deposition

Abstract

Epitaxial growth of silicon-germanium (Si1−xGex: 0 ≤ x ≤ 1) thin films on Si(001) substrate at low temperature has been investigated using reactive thermal CVD. Si2H6 and GeF4 are used as source gases. The results indicate that Si1−xGex (x ≥ 0.99) epilayer can be prepared directly on Si wafer at 350 °C with the degree of strain relaxation up to 98.5%. Etching reaction between GeF4 and the growth surface plays an important role in both improving the crystal quality and suppressing the propagation of dislocations. High quality epitaxial Si1−xGex has been fabricated with a threading dislocation density of ∼7.0 × 105 cm−2 and RMS roughness of 1.44 nm.