Abstract
InGaP layers grown by metal–organic vapor phase epitaxy (MOVPE) often have an In-rich region within several nanometers from the top of the film, which cannot be explained by normal surface segregation theory. This surface segregation deteriorates the interface abruptness of the InGaP/GaAs system, which is attractive for high-performance devices. This segregation in lattice-matched InGaP/GaAs systems can be explained by considering a “subsurface”, where unstable surface layers play an important role in controlling the composition of grown epi-layers. This subsurface is formed at the beginning of crystal growth, and its thickness is in a steady state under normal continuous epitaxial growth. In this study, the existence of a subsurface during the MOVPE growth of InP and InGaP is experimentally confirmed through kinetic analysis involving a flow modulation method. The kinetic parameters, such as the adsorption and desorption rate constants of In and Ga species, and the crystallization rate from the subsurface are estimated from experimental data and are then used to explain the tendency of In surface segregation in InGaP-MOVPE.
Published Version
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