Journal of Physical Studies 25(1), Article 1601 [12 pages] (2021)
DOI: https://doi.org/10.30970/jps.25.1601 THE COMPOSITION MODULATION EFFECT IN GaInPAs SOLID SOLUTIONS AS A MANIFESTATION OF ENERGY RESONANCE AFTER MATERIAL'S SPINODAL DECOMPOSITIONP. P. Moskvin1 , S. I. Skurativskyi1 , O. A. Gromovyi1, W. Sadowski2
1Zhytomyr Polytechnic State University,
103, Chudnivska St., Zhytomyr, 10005, Ukraine,
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The Cahn-Hilliard model concepts are extended to describe the spinodal decomposition of Ga$_x$In$_{1-x}$P$_y$As$_{1-y}$ solid solutions grown on the InP substrate. The energy of elastic deformation of the thin layer of a solid solution was calculated on the assumption of its coherent conjugation with the massive InP substrate. The excess energy of component mixing in the solid phase was modeled in accordance with the simple solution model, when the simultaneous substitution of components in the metal and metalloid sub lattices of the sphalerite structure is incorporated. The system of differential equations describing variations of the composition of a semiconductor solid solution after its spinodal decomposition was solved numerically under various thermodynamic conditions.
The temperature-concentration intervals in which the oscillations of the supersaturated metastable state of the solid phase may take place were found by analyzing the phase portrait of the resulting system of differential equations. We obtained the thermodynamic synthesis conditions ensuring the appearance of the microoscillations of the solid solution composition. It was shown that the development of intensive oscillations (composition modulation effect in material) is caused by the mutual transition of all excess thermodynamic energy of mixing of an unstable solid phase into the energy of elastic stresses of the coherently conjugated layers of decaying material (energy resonance).
The shape of the component concentration profiles in the obtained oscillatory process differs significantly from the shape corresponding to harmonic oscillations. One reason for this is the complex dependence of the models parameters of the distribution on the materials composition. Another reason is that the solutions found are in close proximity to the resonance, which is characterized by a significant increase in the oscillation amplitude and, as a consequence, the manifestation of nonlinear properties of the system. The results obtained clearly illustrate the formation of concentration domains during the spinodal decomposition of the multicomponent semiconductor solid phase.
The results of the parameter calculation for the oscillatory process were compared with the data on the modulation composition effect, which is experimentally observed during the production of elastically strained Ga$_x$In$_{1-x}$P$_y$As$_{1-y}$ heterostructures. The interval of thermodynamic parameters of the growing system which ensures the development of the composition modulation effect in Ga$_x$In$_{1-x}$P$_y$As$_{1-y}$ solid solutions was considered in detail.
Key words: solid solutions, semiconductors $A^3B^5$, crystal structure.