The effect of substrate orientation upon Be transport during GaAs molecular beam epitaxial growth was evaluated by means of secondary ion mass spectrometry and measurements of the current-voltage characteristics of AlGaAs/GaAs heterojunction bipolar transistors. The Be doping level was between 2 x 1019 and 9 x 1019/cm3. The Be transport which was observed for the conventional (100) orientation increased rapidly upon increasing the growth temperature from 530 to 630C. However, with a substrate misorientation away from (100) and towards (111)A, Be transport decreased at 630C and reached a minimum value for the (311)A orientation. The maximum current gain, of AlGaAs/GaAs heterojunction bipolar transistors which had been grown at 560C, was equal to 264 for the (411)A orientation and 3 for the (100) orientation. It was concluded that this confirmed the applicability of substrate orientations other than the conventional (100) one for obtaining a sharp Be profile.

Influence of Substrate Orientation on Be Transport during Molecular Beam Epitaxy of AlGaAs/GaAs Heterojunction Bipolar Transistors.  K.Mochizuki, S.Goto, T.Mishima, C.Kusano: Japanese Journal of Applied Physics, 1992, 31[1-11], 3495-9