Effects of Kikuchi scattering on reflection high-energy electron diffraction intensities during molecular-beam epitaxy GaAs growth

Abstract

Intensity profiles along the specular streak of the reflection high-energy electron diffraction (RHEED) pattern observed during GaAs growth by molecular-beam epitaxy (MBE) show intensity peaks from diffuse scattering processes as well as the specular intensity peak. Intensity oscillations from the diffuse scattering peaks vary in phase with the intensity oscillation at the specular position, with the phase variation depending on the incident angle of the electron beam. Calculation of major Kikuchi line escape angles near the [110] azimuth shows that the diffuse scattering peaks observed are at Kikuchi angles. At some incident angles, interference between Kikuchi and specular scattering is found to change the phase of the oscillation observed at the specular position, as reported by other workers. Interference from Kikuchi processes should be more easily avoided when observing along an azimuth a few degrees off of the [110] direction than when observing directly along the [110] direction. Oscillation phase versus escape angle measurements along an azimuth 7° off [110] show that the phase versus angle curve is somewhat less erratic than that measured directly along the [110] direction by other workers. We still find, however, that the oscillation phase observed at the specular position is shifted over much of the angular range, complicating the common interpretation in which RHEED oscillation maxima correspond to the smoothest growth surfaces.