REFLECTANCE ANISOTROPY SPECTROSCOPY AND THE GROWTH OF LOW-DIMENSIONALMATERIALS

Reflectance anisotropy spectroscopy (RAS) has proved itself to be extr emely sensitive to both surface reconstruction and ultrathin coverages of material on semiconductor surfaces. This in situ technique therefo re lends itself to monitoring the formation of low-dimensional systems in a wide range of growth environments. The following systems have be en studied under molecular beam epitaxy (MBE) conditions: (i) the depo sition of sub-monolayer coverages of Si, to form Si delta-layers withi n GaAs; (ii) the As/P exchange reaction which leads to the formation o f InAs surface quantum wells on the InP(001) surface; (iii) the self-o rganised growth of InAs quantum dots via strain relaxation of ultrathi n layers (< 2 ML) of InAs deposited on the GaAs(001) surface; (iv) the kinetics of hydrogen desorption from vicinal Si(001) surfaces. In our studies of Si/GaAs, it has been possible to deduce both that RAS is s ensitive to coverages greater than or equal to 0.005 ML Si/GaAs, and t o estimate the level of activity of Si donors within a single delta-pl ane. Analysis of time-resolved RAS measurements has led to: an activat ion energy of 1.23 +/- 0.05 eV being determined for the As/P exchange reaction on InP(001); a detailed study of the conditions which influen ce InAs island formation on GaAs; and the suggestion of a new desorpti on pathway for H on vicinal Si(001) surfaces. (C) 1998 Elsevier Scienc e S.A.