Silicon and indium doping of GaAs: Measurements of the effect of doping on mechanical behavior and relation with dislocation formation

Abstract

The effect of indium and silicon doping on dislocation formation in GaAs single crystals has been studied experimentally using dynamic compression tests and indentation rosettes. By direct measurements of the critical resolved shear stress (CRSS) in temperature range from 400 to 1100°C using dynamic compression tests, we found that the· critical resolved shear stress of GaAs:In is twice that of undoped GaAs.More recent measurements show that the critical resolved shear stress of silicon-doped crystals is lower than that of undoped GaAs •. Well-:defined indentation rosettes were obtained at high temperatures from a Vickers indenter using small loads. Analysis of such rosettes confirm that the mechanical behavior of the GaAs crystals is not drastically affected by the presence of dopants. Reduction of dislocation densities in doped crystal s is attributed to modifications introduced by the dopant in the equilibrium concentration of native defects at the melting point (particularly gallium and arsenic vacancies). These values are summarized in Table II.At low temperatures (T<390°C), the CRSS of GaAs:In is less than that of undoped GaAs, while at higher temperatures it is greater. At the melting point, the CRSS of GaAs:In ([InJ = 2.9xlQ19/ cm3) is only twice that of undoped GaAs. The opposite behavior is observed for GaAs:Si. At low temperatures, GaAs:Si is much more resistant to deformation. However, at elevated temperatures the CRSS of GaAs:Si is significantly lower than that of undoped GaAs and more surprisingly decreases with increasing concentration of Si. At a given temperature, the size of the indents increases proportionally to the appl ied load. The ratio of hardness obtained for each load and temperature are summarized in Table III and compared to the ratio of the '" / i ,,-I Indentation

Slip defect generation on GaAs wafers during high temperature process: a thermoelastic study from a crystallographic viewpoint

“…MPa, which approximately agrees with the value reported by Bourret et al [3] at 650°C. In the following calculations we assume o crs = 3 MPa.…”

Investigation of residual dislocations in VGF-grown Si-doped GaAs

“…[4] have shown that the crystal is indeed nearly stress-free in the seed well (s vM o0.1 MPa, with s vM the von Mises stress). This stress level is clearly below the critical resolved shear stress of about 0.3 MPa [33] for Si-doped GaAs. Therefore, no stress-induced dislocations are expected in the seed well.…”

Methods to Decrease Defect Density in GaAs/Si Heteroepitaxy

“…The tensile strain observed experimentally is considerably lower than the expected value 2.4 x I0-3 , indicating strain relief by plastic flow. Cooling from 600°C to only 400°C is sufficient to generate a biaxial tensile stress far above the experimentally determined critical resolved shear stress of 15 MPa at 400°C [27], which will result in the glide of additional threading dislocations of various types from the interface into the epilayer. In addition, misfit dislocations at the interface can be forced to dissociate on a { 111} plane inclined to the interface, leaving one partial dislocation at the interface and forming an extended stacking fault.…”