Aluminum 2p soft-x-ray emission and absorption spectra (XES and XAS) of a G
aAs/AIAs/GaAs heterostructure semiconductor have been measured with high-en
ergy resolution. The Al 2p XES shows a similar feature to that of AlxGa1-xA
s alloys. Strong Al 2p core excitons have been observed in XAS, and attribu
ted to the X- and L-like states in the conduction band. The XAS profile has
changed depending on the incident angle of the excitation x rays. This dep
endence may relate to the symmetry of the exciton transitions. [S0163-1829(
99)01208-4].