Dislocation cell structures in melt‐grown semiconductor compound crystals

Abstract

The phenomenon of dislocation patterning during melt growth of III-V, II-VI and IV-VI semiconductor crystals is discussed. The paper is focused on the formation of cellular structures driven by the growth inherent thermo-mechanical stress. Of particular interest is the scaling of relations between cells size, dislocation density and acting shear stress. Among the materials there are characteristic similarities but also significant variations of the cell genesis. After the related compound specifics are discussed possible measures for retardation of cell patterning during growth are demonstrated.

Dislocation patterning: The role of climb in meso-scale simulations

“…And, of course, we only simulated 2D systems, while the experimental evidences are 2D sections of 3D crystals. It should be stressed that also sharp walls of single dislocation lines are observed in other growth processes, as in telluride crystals [40], similar to the numerically obtained wall structure. There are, however, numerous stray dislocations within cells in [40], while on our Fig.…”

“…5, similarly to earlier, smaller scale simulations [41]. It has been emphasized in [40] that such structures can also be observed in case of doping beyond a threshold, and attributed it to the effect of some dopant as mobility stoppers. Indeed, if slow mobility in any direction greatly increases the time needed to reach some stationary configuration, it may prevent cell formation under a given experimental condition.…”

“…[1,33]). Recent experimental accounts by Rudolph et al [15] and Rudolph [40] focusing on dislocation patterns display characteristic structures, which are worth being compared qualitatively to our results. In melt-grown undoped GaAs crystals dislocations generated by thermal induced strain, but in the absence of post-grown mechanical stress, were visualized on sections by the etch-pit technique as shown in Fig.…”

Micro‐Raman study of strain fields around dislocations in GaAs

“…For convenience the labels L and T are avoided wherever unnecessary. The frequency shift in the presence of stress can be calculated from the eigenvalues ( 1,2,3):…”

“…In the case of a polycrystalline material, for instance, residual stress of the first kind characterises the long-range behaviour of the whole sample, residual stress of the second kind the stress condition within the single grain and the third kind characterises local stress within a grain. Analogously, applying this terminology to monocrystalline SI GaAs wafers residual stress of the second kind refers to the cells in which dislocations are arranged [3] and the third kind to single dislocations or dislocation walls.…”