Real-time monitoring of heteroepitaxial Ga/sub x/In/sub 1-x/P growth on Si(001) by P-Polarised reflectance

We report the application of the real-time optical monitoring techniques p-polarized reflectance (PR) and laser light scattering during low temperature growth of epitaxial GaP/Ga_xIn_1-x P heterostructures on Si(001) and GaAs(001) substrates by pulsed chemical beam epitaxy (PCBE). The high surface sensitivity of PR allows to follow growth processes with sub-monolayer resolution during the sequential precursor exposure of the surface that causes periodic alterations in composition and thickness of a surface reaction layer (SRL), the effect of which is monitored by PR as a periodic fine structure. This fine structure is superimposed on interference fringes, resulting from back reflection at the substrate-layer interface with increasing layer thickness. The amplitude modulation and the turning points in the fine structure are accessed and compared to experimental results, showing that an average complex dielectric function of an ultra-thin SRL can be quantified, independent of the average thickness of the surface reaction layer. The PR response during the growth of Ga _xIn_1-xP correlates as a function of the interference fringe position with the Ga:In composition