NEW PHOTOLUMINESCENCE TRANSITION IN GAAS INVOLVING D- STATES

Low temperature photoluminescence results from high purity epitaxial G aAs are presented, and a new type of transition involving negatively c harged donor ions and neutral accepters is identified. At low temperat ures and excitation densities this becomes the dominant radiative proc ess, with a linewidth of only similar to 1 cm(-1). The temperature dep endence of this new transition reveals a binding energy of 2.65 +/- 0. 35 cm(-1), consistent with the spectroscopic value of 2.8 +/- 0.2 cm(- 1) and with theoretical predictions. This is to our knowledge the firs t experimental determination of the D- binding energy in unperturbed G aAs.