REACTION CHEMISTRY OF ZNTE METALORGANIC VAPOR-PHASE EPITAXY

The reaction chemistry of zinc telluride (ZnTe) metalorganic vapor-pha se epitaxy (MOVPE) from dimethylzinc (DMZn), diethylzinc (DEZn), and d iisopropyltelluride (DIPTe) has been studied using on-line gas chromat ography and infrared spectroscopy. Two growth regimes have been discov ered: one at low values of the II/VI ratio and the other at higher val ues of the II/VI ratio. In the first regime, the group VI compound is consumed in excess, while in the second regime, the group II compound is consumed in excess. The crossover point lies at II/VI = 5.0 for DMZ n and at II/VI = 0.3 for DEZn. Stoichiometric ZnTe is deposited under all growth conditions. The excess DIPTe consumed is converted into vol atile diisopropylditelluride and isopropyltellurol. Conversely, the ex cess DEZn or DMZn consumed produces zinc metal. These waste byproducts accumulate in the outlet of the reactor. The hydrocarbon products gen erated from the ethyl and isopropyl ligands are indicative of radical disproportionation, recombination, and hydrogenation reactions. Howeve r, the methyl ligands mainly undergo surface hydrogenation to produce methane.