Surfactant-mediated epitaxy of Ge on Si: progress in growth and electrical characterization

Smooth, continuous, relaxed, and high quality Ge films have been grown on Si(lll) using surfactant-mediated epitaxy (SME). Using high temperature SME we have reduced the Sb surfactant doping level by more than three orders of magnitude below the solid solubility. This enhanced surfactant segregation is attributed to the formation of an ordered (2 x 1)-Sb reconstruction on the Ge(111) growthfront. With increasing growth temperature the Sb incorporation decreases to I x 10(16)cm(-3) at 700 degrees C. This low Sb doping concentration has been determined by electrical characterization. The electron Hall mobility varies strongly with the doping concentration. Record values of 3159 cm(2)/Vs at 300 K suggest interesting potential of SME grown Ge films for future device applications. Capacitance voltage measurements on vertical p (+)n diodes show a uniform doping profile and are in good agreement with Hail measurements. (C) 1998 Elsevier Science S.A. All rights reserved.