THE MOLECULAR-BEAM EPITAXIAL-GROWTH OF GAAS/GAAS(111)B - DOPING AND GROWTH TEMPERATURE STUDIES

A series of investigations are presented which address various aspects of the growth, by molecular beam epitaxy, of n-type (Si doped) on-axis GaAs/GaAs(111)B. In situ characterization by reflection high-energy electron diffraction has identified four surface phases on the static (zero growth rate) surface, and three reconstructions which occur, depending upon the substrate temperature, during growth. The n-type doping properties of GaAs/GaAs(111)B epilayers have been compared with n-GaAs/GaAs(100) structures. Hall effect and low-temperature photoluminescence measurements have demonstrated that it is possible to dope GaAs/GaAs(111)B with Si in the 6 x 10(14) to 10(18) cm-3 range. A variable growth temperature study is also presented which examines the surface structural, electrical, optical, and surface morphological properties of n-GaAs/GaAs(111)B grown in the 400 to 650-degrees-C temperature range. The onset of electrical conduction, and optically active material, was found to be directly related to changes in the dynamic surface structure. The variable growth temperature study also revealed a temperature regime within which it was possible to significantly improve the surface morphology of on-axis GaAs/GaAs(111)B structures whilst retaining good electrical and optical properties.