EFFECT OF STRAIN ON SOURCE GAS DECOMPOSITION AND GROUP-V DESORPTION IN METALORGANIC VAPOR-PHASE EPITAXY STUDIED BY SURFACE PHOTOABSORPTION

The decomposition rate of source gas and the desorption rate of group V atom were measured by surface photo-absorption during metalorganic vapor phase epitaxy (MOVPE). We found that the decomposition of PH3 on GaAs and InAs surfaces, which produces a large tensile strain, is slower than that on GaP and InP surfaces. We also found that P desorption from P-stabilized GaAs and InAs surfaces, which relieves a large tensile strain, is faster than P desorption from GaP and InP surfaces, respectively. Strain-enhanced desorption was also observed for the As-stabilized InP surface. The difficulty of forming the strained surface bond evidently decreases the rate of decomposition and the ease of breaking the strained surface bond evidently increases the rate of desorption.