Phase Diagram of GaAs (111)B Surface during Metal-Organic Chemical Vapor Deposition Measured by Surface Photo-Absorption

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Abstract
Using surface photo-absorption (SPA), we have investigated GaAs epitaxial growth on a (111)B substrate grown by metal-organic chemical vapor deposition (MOCVD). From reflectivity trace measurement and a comparison of SPA spectra from an MOCVD-grown surface and an MBE-grown surface, we find fast As desorption in MOCVD growth corresponding to the phase transition from an As-rich (2×2) like structure to a (√ 19×√ 19) like structure, and subsequent slow As desorption corresponding to the phase transition from the (√ 19×√ 19) like structure to a Ga-rich (1×1) like surface. We have also obtained a phase diagram with respect to the transition from the As-rich (2×2) like structure to the (√ 19×√ 19) like structure. Specular morphology and sufficient TMG decomposition in high temperature growth are attributed to partial desorption of As-trimers from As-rich (2×2) like surface.