We present the optical and electrical properties of Mg doped GaAs epitaxial
layer with various doping levels grown by molecular beam epitaxy (MBE). Th
e double crystal X-ray diffraction measurement combined with carrier concen
tration results showed that high quality GaAs epitaxial layer was grown by
MBE, even at high doping level. The maximum attainable doping density was N
-A-N-D=1.2 x 10(20) cm (3), which is the highest value known so far. Photol
uminescence, results indicate broadening in line-width and redshift in Mg r
elated peak positions with increase in carrier concentration. These results
could be explained by the overlap of acceptor wave functions and many-body
interactions mainly by bandgap renormalization. (C) 2001 Elsevier Science
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