In situ analysis of surface photoabsorption spectra during InP ALE in metal organic chemical vapor deposition

In situ monitoring of InP atomic layer epitaxy (ALE) by surface photoabsorption (SPA) was performed in low-pressure metal organic chemical vapor deposition. Self-limiting adsorption condition of In species was studied for various TMIn injection times. A grazing incidence X-ray study on the thickness of the film grown by ALE, however, showed that the growth rate did not reach one monolayer (ML)/cycle. The SPA signal trace measured during the InP ALE indicated incomplete PH3 decomposition on the methyl-terminated In surface, and this observation was attributed to the cause of submonolayer growth. We also report a spectroscopic SPA study on the surface state during a cycle of ALE process. The SPA spectrum of the methyl-terminated In surface showed a different line shape at around 1.9 eV (In-dimer region) from that of an In-stabilized surface. But, during H-2 purge at 390 degrees C, this portion of the spectrum was observed to evolve to that of an In-stabilized surface by the desorption of methyl radical. (C) 2000 Elsevier Science B.V. All rights reserved.