As and P Desorption from III-V Semiconductor Surface in Metalorganic Chemical Vapor Deposition Studied by Surface Photo-Absorption

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Abstract
As and P desorption processes from (001) oriented GaAs, InAs, GaP, and InP surfaces during metalorganic chemical vapor deposition are investigated by surface photo-absorption. The reflectivity varies from that of a group V stabilized surfaces, formed by the supply of AsH3 or PH3, to that of a group III metal surface during the desorption of group V species in hydrogen carrier gas. This reflectivity change can be described by first-order kinetics. The rate equation including the activation energy can be obrained from the Arrhenius plot of the desorption rate constants. The desorption rate increases in the order of GaP, GaAs, InAs, and InP in the substrate temperature range of 400∼640°C. The observed desorption activation energies suggest that the desorption species are As2 for GaAs (450∼560°C) and InAs (400∼460°C), P2 for GaP (500∼620°C) and InP (below 390°C), and P for InP (above 390°C).