Temperature dependences of the concentration and mobility of charge carriers of a film of a solid solution $(\mathrm{GaAs})_{1-x-y}(\mathrm{ZnSe})_x(\mathrm{Ge}_2)_y$ grown from a bismuth melt solution

Abstract

The temperature dependences of the electron concentration and Hall mobility of $(\mathrm{GaAs})_{1-x-y} \mathrm{ZnSe})_x(\mathrm{Ge}_2)_y$ epitaxial films grown on $n$-GaAs(100) substrates from a bismuth solution-melt by liquid-phase epitaxy were investigated. The structural, morphological, and electrical transport properties of the epitaxial layers were studied using X-ray diffraction (XRD), scanning probe microscopy (SPM), and Hall-effect measurements. XRD analysis confirmed the formation of single-crystalline epitaxial layers with the zinc-blende structure and a very small lattice mismatch with the substrate, indicating high crystalline quality. SPM observations revealed a uniform nanoscale surface morphology consisting of conical protrusions with heights of approximately $6.5$--$7.5\mathrm{nm}$ and lateral dimensions of $110$--$120\mathrm{nm}$. Hall-effect measurements performed in the temperature range of $303$--$603\mathrm{K}$ showed $n$-type conductivity with an electron concentration of approximately $3.36\times10^{16}\mathrm{cm}^{-3}$, a Hall mobility of about $664\mathrm{cm}^2\mathrm{V}^{-1}\mathrm{s}^{-1}$, and an electrical resistivity of approximately $0.3\Omega\cdot\mathrm{cm}$ at $303\mathrm{K}$. The Hall mobility decreases with increasing temperature following a power-law dependence with an experimentally determined exponent of $m = 2.58 \pm 0.07$, obtained from linear regression of the data. Analysis based on Matthiessen's rule indicates that charge transport is governed by the combined effects of acoustic-phonon scattering, longitudinal optical phonon scattering, and scattering by structural defects. The obtained results demonstrate the high crystalline quality and favorable electrical transport properties of the grown epitaxial films and confirm the potential of the investigated epitaxial films for semiconductor electronic and optoelectronic applications.