IN-SITU MEASUREMENT OF SI-DOPANT CONCENTRATION IN GAAS DURING EPITAXY

Reflection high energy electron diffraction intensity oscillations are found to be shifted in phase by the predeposition of Si atoms on the (100) GaAs surface during molecular beam epitaxy, The shift is related to a change in surface reconstruction and is a linear function of the Si density. It is only observed in a narrow range of GaAs growth para meters. A different behavior is seen for (100) AlAs, which we attribut e to a roughening of the growth front. The phase shift for (100) GaAs is less pronounced on the {01} streaks. This can be explained by a dif ferent surface structure near steps running along [1 $($) over bar$$ 1 0]. (C) 1995 American Institute of Physics.