Fast deposition process for graded SiGe buffer layers

Low-energy plasma-enhanced chemical vapour deposition (LEPECVD) is shown to allow for the synthesis of relaxed graded Si1-x,Ge-x, (0 < x less than or equal to 1) buffer layers at deposition rates above 5 nm/s. On the basis of X-ray reciprocal space mapping, transmission electron microscopy, atomic f orce microscopy and defect etching, the quality of these buffer layers is s hown to be comparable to similar structures grown by other techniques at mu ch lower rates. LEPECVD and molecular beam epitaxy (MBE) have been combined fur the synthesis of modulation-doped Si quantum wells, yielding mobilitie s up to 150000 cm(2)/Vs at 2 K.