Intensive far-infrared optical study on the donor impurity band in the presence of a magnetic field for n-GaAs

We have intensively studied donor impurity bands formed by the ground and excited states in the presence of a magnetic field by means of the far-infrared optical technique. With this view, we have carried out measurements of the impurity cyclotron resonance absorption (ICRA) for hydrogenic donors in n-GaAs. Concerning the optical transition between the 1s and 2p ₊₁ states, the variation of the full-width at half-maximum (FWHM) for the ICRA has been investigated as functions of the donor concentration and the magnetic field. Those dependencies of the FWHM have been discussed in consideration of energy bandwidths of the 1s and 2p ₊₁ states for donors in the presence of a magnetic field. The energy bandwidths have been estimated by use of the tight binding approximation for the linear combinations of atomic orbitals, assuming the simple cubic configuration of donors. The qualitative agreement between experimental results and numerical estimation has been obtained.