Real-time monitoring by spectroscopic ellipsometry and desorption mass spectroscopy during molecular beam epitaxy of AlGaAs/GaAs at high substrate temperatures

摘要

A series of AlGaAs/GaAs depositions were monitored in-situ by spectroscopic ellipsometry and desorption mass spectroscopy, under various substrate temperatures (890 K - 990 K) where non-unity sticking conditions occur. An upper bound on the temperature where AlGaAs/GaAs heterostructures may be grown was determined. Ex-situ cross-sectional transmission electron microscopy verified that the AlGaAs/GaAs layer thicknesses grown by molecular beam epitaxy were accurately determined by spectroscopic ellipsometry at these elevated temperatures. The substrate temperature dependence on Ga desorption rates was consistent with Monte Carlo simulation where desorption from both physisorbed and chemisorbed states were included.