DETERMINATION OF V/III RATIOS ON PHOSPHIDE SURFACES DURING GAS SOURCE MOLECULAR-BEAM EPITAXY

Phosphorus-controlled growth rate of homoepitaxial (100) InP, GaP, and AlP on GaP substrates by gas source molecular beam epitaxy was investigated. Elemental group-III sources and thermally cracked phosphine were used. The growth rat was monitored by the specular beam intensity oscillations of reflection high-energy electron diffraction. This technique gives exact values of V/III ratio on the surface by measuring the amount of phosphorus which is actually incorporated into the film. Here the V/III ratio is defined as P-controlled growth rate divided by group-III-controlled growth rate instead of the beam flux V/III ratio. Also the phosphorus surface desorption activation energies were measured to be 0.61 eV and in the range between 0.89 and 0.97 eV for InP and GaP, respectively.