The use of Be as a p-type dopant in AlxGa1-xAs and in modulation doped
heterostructures grown by molecular beam epitaxy on (311)A oriented s
ubstrates is investigated. Photoluminescence and electrical measuremen
ts reveal that Be is incorporated as an acceptor in (311)A oriented Al
(x)Fa(1-x)As with a slightly greater efficiency than in (100) oriented
AlxGa1-xAs. The optical properties of the (311)A samples are better t
han those of the (100) oriented samples. An estimate of the Be binding
energy yields 32 +/- 4 meV at x = 0.240 +/- 0.004. A two-dimensional
hole gas with a very high mobility (250 000 cm(2)/Vs at 100 mK) and wi
th clear fractional quantum hall effect is formed in the modulation of
Be doped heterostructures grown on the (311)A orientation. (C) 1996 A
merican Institute of Physics.