Roughening aspects of room temperature vapor deposited oligomer thin films onto Si substrates

Growth front scaling aspects are investigated for poly-(p-phenylene–vinylene)-type oligomer thin films vapor-deposited onto silicon substrates at room temperature. For a film thickness d in the range from 15 to 300 nm, commonly used in optoelectronic devices, measurements of the correlation function by atomic force microscopy yields roughness exponents in the range H=0.45±0.04, and an rms roughness amplitude which evolves with film thickness as a power law σ∝dβ with β=0.28±0.05. The non-Gaussian height distribution and the measured scaling exponents (H and β) suggest a roughening mechanism close to that described by the Kardar–Parisi–Zhang scenario which is characteristic of non-surface diffussive growth processes.