Control of epilayer thickness during epitaxial growth of high Ge content strained Ge/SiGe multilayers by RP-CVD

In this work, we have developed a reduced pressure chemical vapor deposition (RP-CVD) epitaxial process to grow strain-balanced Ge/Si0.4Ge0.6 multilayers on 200 mm diameter Si(1 0 0) substrates, via an intermediate relaxed Si0.2Ge0.8/Ge buffer. The results obtained indicate that with proper selection of the epitaxial growth conditions, strain-balanced multilayered heterostructures can be produced with the precise Si0.4Ge0.6 alloy content and control of the strained epilayer thicknesses to within a few monolayers. XTEM analysis clearly resolved very abrupt Ge/Si0.4Ge0.6 heterointerfaces and the sample surfaces were seen, by AFM, to be very smooth with an RMS surface roughness below 1.5 nm.