Laser decomposition of surface adsorbed metalorganics in MOMBE growth of GaP

Abstract

Surface reactions triggered by pulsed laser irradiation for GaP growth were studied with reflection high-energy electron diffraction (RHEED) at a low temperature of 350 °C in metalorganic molecular beam epitaxy using triethylgallium (TEGa) and PH3 for GaP growth. On the laser irradiation, the intensity of RHEED showed an abrupt decrease followed by gradual recovery. The abrupt decrease indicates that adsorbed TEGa on a GaP surface is photo-decomposed by the laser irradiation. The intensity recovery had much dependence on PH3 flow rate, which indicates that the intensity recovery is related with surface reaction between photo-decomposed TEGa and P atoms. This result shows that the decomposition of TEGa by laser irradiation and the formation of GaP occur alternately under continuous supply of source gases.