Yield point of as-grown and predeformed GaAs:Zn

Abstract

Articles you may be interested inOn the Fermi level pinning in as-grown GaInNAs(Sb)/GaAs quantum wells with indium content of 8%-32% J. Appl. Phys.Single crystals of highly Zn-doped GaAs are compressed along ͗123͘ in a constant strain-rate test at temperatures between 330 and 700°C. The yield point is studied for both the as-grown and the predeformed state, the latter achieved by strain-rate and temperature-change tests. For as-grown material two deformation regimes are established. At low temperatures the deformation is governed by a kink mechanism typical for tetrahedrally coordinated semiconductors. The activation energy and the stress exponent are deduced as Uϭ1.44 eV and nϭ3.0, respectively. These values are similar to those obtained for undoped GaAs, thus indicating that Zn additions do not appreciably influence the activation energies of kink formation and migration. Nevertheless, a strong efficiency of Zn for locking dislocations in GaAs is observed. At higher temperatures a different regime emerges, which has been also observed in other highly doped semiconductors, the basic mechanism of which, however, has not yet been elucidated. Material predeformed in the temperature-change test exhibits characteristic deviations. In these experiments the crystals behave as if the point-defect concentration or the locking efficiency of obstacles had been appreciably increased on account of predeformation.