Effect of growth temperature on InGaSb metamorphic layers and the fabrication of InGaSb p-i-n diodes

Metamorphic growth of In0.15Ga0.85Sb on a GaSb substrate is reported using InxGa1−xSb buffer layers compositionally graded in steps of x=0.03. All layers were grown using gas source molecular beam epitaxy with a fixed Sb flux providing an excess group-V overpressure. The growth temperature was varied from 450to540°C. X-ray diffraction analysis was used to determine the effect of growth temperature on relaxation and residual strain. As the growth temperature is increased, cross-sectional transmission electron microscopy (TEM) shows that the number of dislocations threading through the metamorphic layer are reduced. Plan-view TEM yields misfit dislocation density around 108cm−2 and from atomic force microscopy, the surface roughness is ∼1nm. Both surface roughness and dislocation density improves with higher growth temperature. Finally, p-i-n homojunction diodes of various sizes on metamorphic layers were demonstrated.