Enhanced Sb segregation in surfactant-mediated-heteroepitaxy: High-mobility, low-doped Ge on Si

Surfactant-mediated epitaxy (SME) allows the growth of smooth, continuous, relaxed, and principally defect free Ge films directly on Si(111); however, the very high surfactant doping level in the range of the solid solubility limit made them unacceptable for most device applications. By using high temperature SME we have reduced the Sb surfactant background doping level by more than three orders of magnitude. This is attributed to an enhanced surfactant segregation without kinetic limitations. The low Sb incorporation has been determined by an electrical characterization: An electron concentration of 1.1×1016 cm−3 and a very high electron Hall mobility of 3100 cm2/V s at 300 K (12 300 cm2/V s at 77 K) suggest an interesting potential of SME grown Ge films for future device applications.