Theoretical analysis of reflection high-energy electron diffraction (RHEED) and reflection high-energy positron diffraction (RHEPD) intensity oscillations expected for the perfect layer-by-layer growth

Abstract

Predictions from two theoretical models, allowing one to determine the phase of intensity oscillations, are compared for reflected beams of electrons and positrons. Namely, results of the precise dynamical calculations are compared with results obtained using a simplified approach. Within the simplified model, changes in the specularly reflected beam intensity, expected to occur during the deposition of new atoms, are described with the help of interfering waves and the effect of refraction, and respective approximate analytical formulas are employed to determine the phase of the oscillations. It is found that the simplified model is very useful for understanding the physics ruling the appearance of intensity oscillations. However, it seems that the model with the realistic potential is more suitable for carrying out interpretations of experimental data.

Calculations of RHEED and RHEPD Rocking Curves for Growing Surfaces of Germanium

“…where θ c is the critical angle, K is magnitude of the wave vector and v av is the volume average potential inside the crystal bulk [7]. For the assumed energy of 15 keV, the value of K 2 is equal to 3994.3 Å −2 .…”

“…Moreover, to run the calculations for positrons, one can use the same computer program as for electrons when changing the sign of the real part of the scattering potential to account the change of the particle charge [7]. It seems interesting to compare theoretical results for RHEED and RHEPD for assumed continuous deposition of material on a substrate.…”

“…It means that during the growth only one incomplete atomic layer exists at the surface. Intensities of reflected electrons and positrons were calculated as described in [7]. Namely, for full layers, the scattering potential was averaged in the z-planes (i.e.…”