Extrinsic effects in reflection high-energy electron diffraction patterns from MBE GaAs

Journal Article · Sun Apr 01 04:00:00 EST 1984 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.582795· OSTI ID:6755087

Pukite, P R; Van Hove, J M; Cohen, P I

One uncontrolled parameter of MBE growth on GaAs is the orientation of the substrate. Typical material is oriented to within 1/2 /sup 0/ of a low-index bulk plane so that the resulting surface consists of a staircase with random terrace lengths and step heights. These steps are important since at room temperature they can orient epitaxial layers and at high temperatures the terrace lengths can be comparable to diffusion distances. Ordered step arrays can also be an important factor in the formation of the characteristic streaked RHEED pattern. We have measured the profiles of these streaks from different wafers with nominally GaAs(001) surfaces and have observed striking differences which we ascribe to ordered staircase steps due to crystal misorientation. Misorientations as small as 1 mrad have been found. Surfaces in which the misorientation from the (001) was about 6.5 mrad were studied extensively and a reciprocal lattice was constructed from a map of the diffracted intensity vs scattering angles. On surfaces misoriented by 1/sup 0/, RHEED oscillations were found to be much weaker than on the 6.5 mrad surface. Differences in the oscillations when the beam was directed first down and then perpendicular to the staircase direction were also observed, but these cannot yet be separated from differences due to temperature and flux ratios.

• Research Organization: Department of Electrical Engineering, University of Minnesota, Minneapolis, Minnesota 55455
• DOE Contract Number: AC02-80ER10583
• OSTI ID: 6755087
• Journal Information: J. Vac. Sci. Technol., B; (United States), Journal Name: J. Vac. Sci. Technol., B; (United States) Vol. 2:2; ISSN JVTBD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
360602 -- Other Materials-- Structure & Phase Studies
ARSENIC COMPOUNDS
ARSENIDES
COHERENT SCATTERING
DIFFRACTION
DIFFUSION
ELECTRON DIFFRACTION
EPITAXY
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
MOLECULAR BEAM EPITAXY
ORIENTATION
PNICTIDES
SCATTERING
SUBSTRATES