Arsenic flux interruptions: Induced RHEED oscillations and measurements of As coverage on the growing (001) MBE GaAs surface

• Published in: Journal of crystal growth 1989-05, Vol.96 (1), p.19-26
• Main Authors: Farley, C.G., Sullivan, G.J., Mondry, M.J., Miller, D.L.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface and interface dynamics and vibrations; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(89)90271-6

The effect of interruption of As flux on the growing (001) MBE GaAs surface has been studied using measurements of the specular intensity of the RHEED pattern. These studies provide new information about the growing GaAs surface. On a growing roughened surface, oscillations in the specular intensity can be initiated by interrupting the As flux for short intervals, i.e., less than GaAs monolayer formation times. The magnitude of the induced ocillations is a maximum when all the excess As on the surface is consumed during the interruption but no excess Ga is deposited. By measuring the time required for the growing surface to convert from As-stable to Ga-stable, the excess As population on the growing GaAs surface has been measured for the first time. This population is not simply related to the difference between the As and Ga fluxes, but is strongly affected by the reconstruction present on the surface. We observe two distinct (2×4) reconstructions on the growing (001) GaAs surface. Using the measured As population and periodicity of the RHEED pattern for several incident electron beam azimuths as constraints, we have specified probable atomic configurations for the (001) As-stabilized (2×4) GaAs surface during growth.