Hole transport properties of B-doped relaxed SiGe epitaxial films grown by molecular beam epitaxy

Transport properties of holes in B-doped relaxed Si1-xGex epitaxial films grown by molecular beam epitaxy have been investigated by Hall measurements. The dependence of the Hall mobility on the Ge content x (0.2-0.82) and on the hole density (1.5 x 10(16)-1.2 x 10(18) cm(-3)) has been measured. From the temperature dependence of hole density estimated by Hall measurements, the ionization energy of the Boron atoms in the relaxed Si0.7Ge0.3 alloys is determined to be 22.7 meV. It is also shown that scattering caused by the random distribution of the Ge atoms in the films offsets the mobility enhancement due to reduction of effective mass in the Si1-xGex films. (C) 2002 Elsevier Science B.V. All rights reserved.