SHALLOW DONOR LEVELS OF INSB IN A MAGNETIC FIELD

We consider, in the effective mass approximation, the problem of a hydrogenic atom in a strong static magnetic field. The ground state and the lowest lying states of angular momentum ± h{stroke} are calculated variationally, first for a simple parabolic conduction band and then for the nonparabolic conduction band of InSb. Both the use of improved variational trial functions and the incorporation into the theory of the nonparabolic conduction band are novel features of the present calculation. The results are compared with previous work. Nonparabolic effects are found to be significant for the energy of the lowest lying state of angular momentum +h{stroke}. The weak-coupling polaron theory is used to derive an upper bound to the shift of the ionization energy of the ground state of the impurity due to electron-LO phonon interaction. Polaron effects on the ground state ionization energy are thereby shown to be negligible in InSb. The bound obtained may, however, prove useful in estimating polaron effects in materials with larger coupling constants. © 1968.