OPTICAL-DETECTION OF GROWTH OSCILLATIONS FROM HIGH-VACUUM UP TO LOW-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY LIKE CONDITIONS

We report optical, real-time detection of growth oscillations for pressures up to low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) like conditions. The measurements were performed using the reflectance difference technique during epitaxial growth of GaAs in a vacuum chemical epitaxy (VCE) chamber in which the LP-MOVPE conditions were obtained by adding hydrogen. Growth oscillations could still be obtained over a wide range of V/III ratios at pressures in the mbar range. Under LP-MOVPE conditions we could observe oscillation amplitudes comparable to those found under VCE conditions. Furthermore, the occurrence of oscillations when hydrogen is introduced shows that the layer-by-layer growth is not affected by the presence of hydrogen. These results seem to open the way for the in situ detection of growth oscillations even in conventional MOVPE systems.