The effects of zinc-doping on the composition of InGaAsP layers grown by MOCVD

• Effects of Zn-doping process on the growth of various InGaAsP alloys were analysed.
• Compositional variation, reductions in growth rate and lattice constant were observed due to doping.
• Independent of composition, TMGa/TMIn decomposition ratio increases with increasing DEZn flow.
• The dependence of arsenic/phosphorus incorporation on DEZn flow depends on InGaAsP composition.
• Compositional variation is the primary cause of the observed tensile strain.

We report on the effects of Zn-doping using diethylzinc (DEZn) on the growth of In1−xGaxAsyP1−y quaternary layers (x=0.18–0.41 and y=0.34–0.76) by metalorganic chemical vapour deposition. Independent of the quaternary layer compositions, a systematic reduction (increase) in Indium (Gallium) was observed. This was accompanied by a reduction in the overall growth rate, and increased tensile strain, with increasing DEZn flow. In contrast, the dependence of arsenic/phosphorus incorporation on DEZn flow was found to depend on the surface stoichiometry. We show quantitatively that the observed tensile strain can be explained by compositional variations caused by the Zn-doping process. These results suggest that DEZn affects both homogeneous and heterogeneous processes during the growth of InGaAsP layers.