DETERMINATION OF EXCESS PHOSPHORUS IN LOW-TEMPERATURE GAP GROWN BY GAS-SOURCE MOLECULAR-BEAM EPITAXY

GaP films, epitaxially grown at a low temperature (LT) of similar to 2 00 degrees C by gas source molecular beam epitaxy, were reported recen tly to have excess phosphorus. In this letter, we report on the quanti tative determination of the excess phosphorus in the LT films, using v arious approaches. Analytical scanning transmission electron microscop y, double-crystal x-ray diffraction, and particle-induced x-ray emissi on showed that the LT GaP films incorporated excess phosphorus of simi lar to 0.6-2 at. %. The amount of excess phosphorus estimated from Ram an scattering measurements, using the LO-TO phonon frequency splitting data of the as-grown LT GaP and bulk GaP, was in general agreement wi th those obtained from other techniques.