Dislocation multiplication in GaAs : inhibition by doping

Abstract

The crystal quality improvement by electrical or isoelectronic doping of L.E.C. grown GaAs crystals is related to the thermoelastic modelling of stresses during growth. The dislocation structure in as-grown and annealed crystals is deduced, in particular with the help of the results of plastic deformation. The addition of various elements of the columns II-III-IV-V-VI in GaAs is considered and its influence on the establishment of the dislocation substructure is discussed

Dislocation cell structures in melt‐grown semiconductor compound crystals

“…2 shows an image of dislocation cells of an as-grown 6" VCz GaAs crystal taken by x-ray synchrotron topography. The dislocations are accumulated in fuzzy walls of certain thickness (50 -100 µm) as was likewise reported elsewhere [9,24,43,44,45]. Typically, numerous junctions and pins form a sessile dislocation jungle (see also refs.…”

“…However, as was shown by Tuomi et al [44] also differing glide systems like for edge dislocations within the {110} planes have been detected. Similar to that in post-deformed samples the dislocation in the walls belongs to the basal glide system <110>{111} too [9]. Obviously, glide processes play an important role for the DD at both high and low temperatures.…”

“…Dislocation cells are also a characteristic feature in post-deformed GaAs specimens showing, however, much higher dislocation densities in the region of ρ = 10 8 -10 10 cm -2 . Much work has been done on the macroscopic deformation behaviour and dislocation structure of GaAs semiconductor crystals after plastic deformation at temperatures T/T m ≤ 0.9 (T m -melt temperature = 1511 K) [8,9,10,39,40]. Important plasticity parameters were determined by these experiments like stress-deformation curves, critical resolved shear stress, dislocation multiplication and motion rates etc.…”

“…It is noteworthy that the formation of spatial cellular patterns is only possible when three-dimensional dislocation movements like cross-glide and climb can take place. Djemel et al [9] pointed out that cross glide is the major step in formation of the microstructure in post-deformed GaAs. Recently, also Madec et al [81] ascribed the pattern formation dynamics priority to cross-slip mechanism which, however, can proceed effectively only in case of relatively high stacking fault energy.…”

Elemental Dislocation Mechanisms Involved in the Relaxation of Heteroepitaxial Semiconducting Systems

“…C and 600 C is approximately v 750 av 600 % 10 (activation energy 1.2 eV [25]) and the length of misfit dislocations is nearly in the same proportion (the thickness and the deposition time are similar).…”