Recent Advances in the Modeling of Strain Relaxation and Dislocation Dynamics in InGaAs/GaAs (001) Heterostructures

In this paper we describe state-of-the-art approaches to the modeling of strain relaxation and dislocation dynamics in InGaAs/GaAs (001) heterostructures. Current approaches are all based on the extension of the original Dodson and Tsao plastic flow model to include compositional grading and multilayers, dislocation interactions, and differential thermal expansion. Important recent break-throughs have greatly enhanced the utility of these modeling approaches in four respects: i) pinning interactions are included in graded and multilayered structures, providing a better description of the limiting strain relaxation as well as the dislocation sidewall gettering; ii) a refined model for dislocation-dislocation interactions including zagging enables a more accurate physical description of compositionally-graded layers and step-graded layers; iii) inclusion of back-and-forth weaving of dislocations provides a better description of dislocation dynamics in structures containing strain reversals, such as strained-layer superlattices or overshoot graded layers; and iv) the compositional dependence of the model kinetic parameters has been elucidated for the InGaAs material system, allowing more accurate modeling of heterostructures with wide variations in composition. We will describe these four key advances and illustrate their applications to heterostructures of practical interest.

A Zagging and Weaving Model for Dislocation Interactions in Heterostructures Containing Strain Reversals

Strained-layer superlattices (SLSs) have been used to modify the threading dislocation behavior in metamorphic semiconductor device structures; in some cases they have even been used to block the propagation of threading dislocations and are referred to in these applications as “dislocation filters.” However, such applications of SLSs have been impeded by the lack of detailed physical models. Here we present a “zagging and weaving” model for dislocation interactions in multilayers and strained-layer superlattices, and we demonstrate the use of this model to the threading dislocation dynamics in InGaAs/GaAs (001) structures containing SLSs.