Modification of strain relaxation process by Si doping in metamorphic Al(Ga)InAs layers grown on GaAs
We investigated the effects of Si doping on the dislocation movements in the compositionally step-graded Al(Ga)InAs buffers grown by metal-organic chemical vapor deposition (MOCVD) on (001) GaAs substrates with 7° miscut toward (111)A. It is found that Si doping suppresses the In segregation and the formation of phase separation in the Al(Ga)InAs buffers to reduce the surface roughness and the threading dislocation density in InP cap layer. In particular, Si substitutes group III atoms as n-type doping for incorporating into B-type step along the  direction and the effect of Si incorporation on the movement of β dislocations is obvious, which consequently promotes β dislocations to glide in the interface and reduces the β threading dislocation densities. While Si impurity has a great ability to lock α dislocations on the (111) slip planes and eventually change the tilt in the  direction. Since doping is essential for many types of optoelectronic devices, these results are valuable for improving the material properties and performance of metamorphic devices.
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Document Type: Research Article
Publication date: December 1, 2016
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