Magnetospectroscopy of Be in GaAs

Far-infrared absorption measurements have been made of the Lyman series of the acceptor Be in GaAs up to magnetic fields of 30 T, supplemented by photothermal ionization spectroscopy measurements to 6 T. The results confirm and greatly extend previous work and reveal several phenomena. The strongest component of the G line moves to higher energies and increases in intensity with field. Around 20 T the field dependence of the transition displays a marked kink. At higher fields the dependence of energy on field is linear. This behavior is attributed to unresolved components that change in relative intensity with field and leads to a reappraisal of the identity of the low-field transition. The D line is followed to high fields allowing an accurate determination of the splitting of the field-induced components of the second excited state. Photothermal ionization spectra for the C line permit the determination of the splitting of the field-induced components of the ground state and of the third excited state. At high magnetic field an absorption appears which increases in energy with field at a much greater rate than any of the lines mentioned above. It is thought to originate in the valence-band Landau levels.