Origin of RHEED intensity oscillation during homoepitaxial growth on Si(001)

•Two possible origins of RHEED intensity oscillations during growth are found.•One is interference between waves diffracted by the top and the subsequent layers.•The other is the disturbance of the RHEED electron waves by step edges.•An approximate measure of the disturbance of electron waves by steps is introduced.

The origin of RHEED intensity oscillations or variations during growth is analysed by using RHEED intensity distributions calculated from wave functions inside and outside the crystal surface. When the growth proceeds in a layer by layer fashion and the observed intensity is near a diffraction peak, there are only two possible origins of the intensity variations. One is the interference between waves diffracted by the top and the subsequent underlying layers, and the other is the disturbance of the RHEED electron waves by step edges. RHEED rocking curves are computed and the intensities of peaks in the curves are found to vary systematically when material is deposited on the surface. The mechanism of these variations is identified by computing RHEED intensity distributions. An approximate measure of the disturbance of the wave function by step edges is also introduced.