In Situ Optical Observation and Control of Initial Stages of GaAs Growth On Caf2 Surface Modified by Electron Beam Irradiation

We investigated the electron beam induced surface modification of CaF2(1 11) and initial stage of GaAs growth on the modified CaF2 surface by means of the surface photoabsorption technique and atomic force microscopy (AFM). The CaF2 surface was modified by 300 eV electron beam irradiation at 200°C in a As4 molecular beam. The amount of adsorbed As atoms increased with electron dose and it follows Langmuir adsorption principle and saturated at a value equivalent to I monolayer adsorption. In situ observation of GaAs growth on this modified surface clarified that the sticking coefficient of GaAs on CaF2 surface was drastically improved by the surface modification. AFM observation revealed that the surface roughness of initial growth of GaAs on modified CaF2 was improved at the growth temperature of 550°C