FAR-INFRARED ABSORPTION SPECTRA AND THE ENERGY LEVELS OF SHALLOW ACCEPTOR IMPURITIES IN InSb.

Study was made of the far-infrared absorption spectra (50-2400 mu ) of shallow acceptor impurities (zinc and germanium) in indium antimonide, for uncompensated impurity concentrations in the range 4 multiplied by 10**1**2 to 1. 1 multiplied by 10**1**6 cm** minus **3 at 1. 5 degree K. A theoretical calculation of the energy structure of shallow acceptor impurities in indium antimonide was made, using the effective mass approximation, in order to interpret the observed absorption lines and establish the structure of both the ground and excited states of these impurities. The binding energies of zinc and germanium impurities in indium antimonide were thus determiend to be 9. 1 multiplied by 10** minus **3 and 9. 25 multiplied by 10** minus **3 eV respectively, and the energies of several of the lower excited states were also determined. Absorption at the longest wavelengths was observed as the germanium concentration in indium antimonide was increased, and this is associated with the splitting of the ground state of the impurities by their exchange interaction.