A first comparative study was made of recombination mechanisms between doped and undoped p-type liquid-phase epitaxial films. The doped films were Cu- or Au-doped, with carrier concentrations that ranged from 2 x 1015 to 1.5 x 1017/cm3. Undoped (Hg-vacancy) films had carrier concentrations which ranged from 3 x 1015 to 8 x 1016/cm3. It was found that, for a given carrier concentration, doped films had lifetimes which were several times longer than those of undoped films. The ineffectiveness of the Shockley-Read-Hall recombination process in doped films was reflected by lifetime versus temperature curves. A reduction of minority carrier lifetime in undoped films could be explained by an effective Shockley-Read-Hall recombination center that was associated with the Hg vacancy. The existence of a donor-like Shockley-Read-Hall recombination center that was located at the mid-gap (Ev + 0.06eV), with a capture cross-section for minority carriers that was much larger than that for majority carriers, was deduced from lifetime versus temperature curves for undoped films.

M.C.Chen, L.Colombo, J.A.Dodge, J.H.Tregilgas: Journal of Electronic Materials, 1995, 24[5], 539-44