Data were presented on the reduction of layer intermixing in quantum-well heterostructures, during high-temperature annealing, by using an initial low-temperature blocking diffusion of Zn. Room-temperature photoluminescence measurements of the increase in the lowest electron to heavy-hole transition energy in the quantum-wells were used to characterize the extent of layer intermixing. Doped (C and Si) samples which had been annealed (850C, 12h) after a low-temperature blocking Zn diffusion (480C) exhibited reductions in energy shift from about 0.177eV, to as little as 0.018eV. Similar effects were observed, but to a lesser extent, in the case of undoped samples. The improved thermal stability was attributed to a Zn diffusion-induced reduction in the number of column-III vacancies in the active layers. This was confirmed by secondary-ion mass spectroscopy measurements.

M.R.Krames, A.D.Minervini, E.I.Chen, N.Holonyak, J.E.Baker: Applied Physics Letters, 1995, 67[13], 1859-61