Roughening rates of strained-layer instabilities

We study the evolution of the morphology of Si_0.75Ge _0.25 strained layers using a wide range of deposition times, 60 < τ < 2400 s, at 600°C on laser textured substrates with miscuts θ < 15° off Si(001). Ripple-shaped morphologies form spontaneously on miscuts along the 〈110〉 directions. At the shortest deposition times, roughening is suppressed as predicted by a linear stability analysis that uses previously measured values for the mass transport rate on the surface. The measured time constant of the roughening is ≈ 80 s, a factor of 4 larger than predicted by theory.