Application of Reflectance Difference Spectroscopy (RDS) to Migration-Enhanced Epitaxy (MEE) Growth of GaAs

Abstract

Differences in the reflectance of light polarized along the [110] and [11̄0] directions of the (001) GaAs surface are detected with a simple optical setup and used as an in-situ analysis and control tool for migration-enhanced epitaxial growth. The reflectance difference (RD) signals during successive surface exposures to Ga and As₄ beams at various substrate temperatures are analyzed and correlated to the surface reconstruction and the fractional surface coverage, on the basis of current models of the (001) GaAs surface and nucleation of Ga–Ga dimers. A new negative component of the RD signal is tentatively attributed to Ga nucleation and accumulation along [110] terrace edges. Finally, RD periodic signal analysis during a stationary MEE growth process is used to determine the most appropriate growth conditions.