COMPOSITIONAL GRADIENTS IN GAXIN1-XAS ON PATTERNED INP SUBSTRATES GROWN BY ATMOSPHERIC-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY

The growth rate and composition of GaxIn1-xAs layers on nonplanar InP substrates deposited in the MOVPE process at atmospheric pressure using the precursors trimethylgallium-trimethylamine (TMGa-TMN) and trimethylindium-trimethylamine (TMIn-TMN) were investigated. Comparing the growth rates r on the different (001) areas of the nonplanar substrate, we found that r(ridge) > r(planar) > r(groove). Studying the composition of the GaxIn1-xAs on planar substrates, we observed x(Ga)(001) > x(Ga){111}A > x(Ga){111BAR)B. Similarly, on patterned samples the (001) plane is that with the highest gallium concentration. On the (001) plane of the nonplanar substrate, the tendency x(Ga)(ridge) < x(Ga)(planar) < x(Ga)(groove) was observed. Superimposed on this we observed, adjacent to the polar {111} planes, lateral composition gradients, which depend on the orientation of the sidewalls. The experimental results are discussed, using a stagnant boundary layer model. Different reactivities of the Ga- and In-organometal compounds are considered.