Reorientation of Misfit Dislocations During Annealing in InGaAs/GaAs( 001) Interfaces

ABSTRACTTransmission electron microscopy is applied to investigate the effect of post-annealing on misfit dislocations in an In0.2Ga0.8As/GaAs(001) heterostructure. An orthogonal array of 60º dislocations along [110] and [110] directions was observed in the interfaces of the samples grown by MBE at 520 ºC. When the as-grown samples were annealed at temperatures ranging from 600 to 800 ºC, the 60º dislocations were gradually reoriented by dislocation reactions occurring at the 90º intersections followed by nonconservative motion driven by dislocation line tension and the residual elastic misfit strain. The final result of this process was a dislocation array lying along [100] and [010] directions. The reoriented u=&lt;100&gt; dislocation has a Burgers vector , which is the same as that of 60º dislocation, but the edge component of its Burgers vector in the (001) interfacial plane is larger than that of 60º dislocation by a factor of , resulting in a greater contribution to elastic strain relaxation. This nonconservative reorientation of 60º dislocations to form the u=&lt;100&gt; dislocations represents a new strain relaxation mechanism in diamond or zinc blende semiconductor heterostructures.</jats:p

Galileo's stream: A framework for understanding knowledge production

We introduce a framework for understanding knowledge production in which: knowledge is produced in stages (along a research to development continuum) and in three discrete categories (science and understanding, tools and technology, and societal use and behavior); and knowledge in the various stages and categories is produced both non-interactively and interactively. The framework attempts to balance: our experiences as working scientists and technologists, our best current understanding of the social processes of knowledge production, and the possibility of mathematical analyses. It offers a potential approach both to improving our basic understanding, and to developing tools for enterprise management, of the knowledge-production process.

A Test of Two Solute Trapping Models

Engineering and Applied Science

Reorientation of misfit dislocations during annealing in InGaAs/GaAs(001) interfaces

Transmission electron microscopy is applied to investigate the effect of postannealing on misfit dislocations in an In[sup 0.2]Ga[sup 0.8]As/GaAs(001) heterostructure. An orthogonal array of 60[degree] dislocations along [110] and [110] directions was observed in the interfaces of the samples grown by MBE at 520C. When the as-grown samples were annealed at temperatures ranging from 600 to 800C, the 60[degree] dislocations were gradually reoriented by dislocation reactions occurring at the 90[degree] intersections followed by nonconservative motion driven by dislocation line tension and the residual elastic misfit strain. The final result of this process was a dislocation array lying along [100] and [center dot] [010] directions. The reoriented u = dislocation has a Burgers vector b = a/2 , which is the same as that of 60[degree] dislocation, but the edge component of its Burgers vector in the (001) interfacial plane is larger than that of 60[degree] dislocation by a factor of [radical]2, resulting in a greater contribution to elastic strain relaxation. This nonconservative reorientation of 60[degree] dislocations to form the u= dislocations represents a new strain relaxation mechanism in diamond or zinc blende semiconductor heterostructures