ACCEPTOR EXCITATION-SPECTRA IN GERMANIUM IN A UNIFORM MAGNETIC-FIELD

The irreducible-spherical-tensor form of the effective-mass Hamiltonians for acceptors in cubic semiconductors in a homogeneous magnetic field parallel to a <001> direction or to a <111> direction has been derived. The Hamiltonians take into account the full structure of the GAMMA-8+ + GAMMA-7+ valence-band edge, and they contain a point-charge potential with spherically symmetric q-dependent dielectric screening. The eigenstates have been calculated variationally for the case of acceptors in germanium. For both orientations, the computations have been performed as a function of the magnetic-field strength, in the range from 0 to 5 T. The binding energies of the first 36 odd-parity excited states and of the first 4 even-parity states (which form the ground-state multiplet) are obtained. The oscillator strengths of the electric-dipole transitions from the ground-state sub-levels to the excited states are also calculated, and the results are used to simulate theoretical acceptor excitation spectra, which are in excellent agreement with the available experimental far-infrared-absorption and photothermal-ionization-spectroscopy spectra. For the ground state and for the final states of the G and D lines, theoretical g factors are obtained which are very close to the experimental ones. In particular, the values g1' = -0.45 and g2' = +0.22 are computed for the acceptor ground state. It is found also that for the ground state and for the excited GAMMA-8(TdBAR) final states of the G, D, and B spectral lines, the ratio r = g2/4g1 is always very close to the special value -5/41, which corresponds to a linear Zeeman splitting of the GAMMA-8 states into a degenerate doublet for B parallel-to <111> and into an equally spaced quartet for B parallel-to <001>.