REFLECTANCE ANISOTROPY FROM NON-III-V SYSTEMS - SI AND SIGE GROWTH ON(001)SI AND ADSORBATE-INDUCED RECONSTRUCTION OF CU(110)

Reflectance anisotropy (RA) data are presented for the study of two di screte systems - the dynamic growth of Si and SiGe on Si(001) and the formation of ordered overlayers on Cu(110). In the first of these stud ies first examples are presented of high quality RA oscillations and s imultaneously recorded RHEED oscillations obtained during the growth o f Si and SiGe on Si (001) by gas source MBE using disilane and germane at temperatures of 600 degrees C. RA measurements clearly demonstrate an enhancement in growth rate upon introduction of germane to the dis ilane flow. For both systems, the RA was found to oscillate at a perio d corresponding to bilayer growth which is explained in terms of a mod el based upon the changes in relative domain size and hence Si dimer ' 'concentration'' on the two orthogonal [110] azimuths. The RA data are also compared with variations in the total reflectance of the growing surfaces which is recorded simultaneously. In the second study it is demonstrated here that the RA technique may also be applied to the stu dy of surface processes occurring at a metal single crystal surface. A marked RA response was observed from a Cu(110) single crystal under c onditions where adsorption of O-2, O-2 + formic acid, and benzoic acid results in a re-structuring of the surface as determined independentl y using LEED. Dynamic RA responses corresponding to (R(<1(1) over bar 0>) - R(001))/R(tot) are correlated with exposure of the various adsor bates and the appearance of particular overlayer structures. It is sug gested that the RA response observed comes from a quenching of an allo wed surface transition of the clean Cu(110) surface by the electronic perturbation induced by the adsorbates. If correct, this explanation w ould add much weight to the currently held interpretation of RA data f rom III-V systems which invokes similar geometrically oriented surface state transitions. However, at present, the possibility of involvemen t of new adsorbate-induced surface states cannot be ruled out.