OPTICAL SPECTROSCOPY OF EXCITONIC STATES IN ZINC DIARSENIDE

The luminescence and transmission of zinc diarsenide single crystals n ear the fundamental absorption edge have been investigated in the temp erature range 4.2-300 K. Intense luminescence and absorption lines at 1.0384, 1.0488, and 1.0507 eV, referring to the ground state (n=1) and excited states (n=2, n=3) of a free exciton were observed at low temp eratures. The free-exciton binding energy was found to be similar to 1 3.9 meV on the basis of the hydrogen-like model and the direct band ga p was found to be 1.0523, 1.0459, and 0.9795 eV at 4.2, 78, and 300 K, respectively. (C) 1997 American Institute of Physics.