We have performed RHEED measurements over a wide range of growth temperatures and rates on Si(001) substrates. The measurements of the equilibrium intensity, the oscillation amplitude and the damping constants of the oscillations show a very systematic behaviour. RHEED oscillations at a growth rate of 0.1 Angstrom/s are found for a wide temperature region between 300 and 750 K. This temperature window shifts systematically to higher temperatures for higher growth rates.