Sr. Armstrong et al., PHOTOELECTROCHEMICAL ETCHING OF N-GAAS(001) ELECTRODES STUDIED USING REFLECTANCE ANISOTROPY, Surface science, 309, 1994, pp. 1028-1032
We demonstrate here that the novel ''epioptic'' technique of reflectan
ce anisotropy (RA) is capable of detecting in real time, variations in
the optical anisotropy of an GaAs(001) electrode surface during anodi
c oxidation in aqueous KCl solutions. A novel system is described in w
hich the exciting probe laser beam also excites minority charge carrie
rs (boles) in the n-type materials thus giving rise to the photoelectr
ochemical oxidation reaction. The influence of the neutral additive py
ridine upon the etching kinetics is described while the nature of the
changes in surface structural anisotropy are discussed in terms of pos
sible surface reconstruction in aqueous solution, the appearance of hi
ghly oriented macroscopic etch features and the possible formation of
oriented surface layers.