FORMING OF AL-DOPED ZNTE EPILAYERS GROWN BY MOLECULAR-BEAM EPITAXY

We have studied the effects of forming (annealing under bias) on Al-doped ZnTe epilayers grown by molecular beam epitaxy. These experiments verify the existence of forming effects at the temperatures and biases assumed in a model of this method of contacting lightly doped, wide band gap II-VI materials. Such contacts are of particular interest in light emitting structures requiring contacts to II-VI materials, such as ZnSe:N, which cannot be doped to high carrier concentrations. The structures we studied in these experiments consisted of thin (generally 800 angstrom) layers of ZnTe doped with Al concentrations of 1.9 x 10(19) cm-3, grown on p-type ZnTe substrates and contacted with Zn applied in situ. We studied changes in the current-voltage characteristics of these devices during and after forming at 210-degrees-C under biases less than 1.5 V.