Fast Deposition Process for Graded SiGe Buffer Layers

Abstract

Low-energy plasma-enhanced chemical vapour deposition (LEPECVD) is shown to allow for the synthesis of relaxed graded Si1-xGex, (0≤x≤1) buffer layers at deposition rates above 5 nm/s. On the basis of X-ray reciprocal space mapping, transmission electron microscopy, atomic force microscopy and defect etching, the quality of these buffer layers is shown to be comparable to similar structures grown by other techniques at much lower rates. LEPECVD and molecular beam epitaxy (MBE) have been combined for the synthesis of modulation-doped Si quantum wells, yielding mobilities up to 150000 cm2/Vs at 2 K.