Relaxed InxGa1−xAs graded buffers grown with organometallic vapor phase epitaxy on GaAs

${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{As}$ structures with compositionally graded buffers were grown with organometallic vapor phase epitaxy on GaAs substrates and characterized with plan-view and cross-sectional transmission electron microscopy, atomic force microscopy, and x-ray diffraction. The results show that surface roughness experiences a maximum at growth temperatures where phase separation occurs in ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{As}.$ The strain fields from misfit dislocations induce this phase separation in the 〈110〉 directions. At growth temperatures above and below this temperature, the surface roughness is decreased significantly; however, only growth temperatures above this regime ensure nearly complete relaxed graded buffers with the most uniform composition caps. With the optimum growth temperature for grading ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{As}$ determined to be 700 °C, it was possible to produce ${\mathrm{In}}_{\mathrm{0.33}}{\mathrm{Ga}}_{\mathrm{0.67}}\mathrm{As}$ diode...