Abstract:
Single-crystal films of the substitutional solid solution (GaAs)$_{1-x}$(ZnSe)$_x$ (0 $\le x\le$ 0.80) on GaAs substrates have been grown using liquid phase epitaxy. The X-ray diffraction patterns, photoluminescence spectra, and current-voltage characteristics of the $n$-(GaAs)–$p$-(GaAs)$_{1-x}$(ZnSe)$_x$ (0 $\le x\le$ 0.80) heterostructures prepared have been investigated. The lattice parameters of the film $a_f$ = 5.6544 $\mathring{\mathrm{A}}$ and the substrate $a_s$ = 5.6465 $\mathring{\mathrm{A}}$ have been determined, and the profile of the molecular distribution of the solid solution components has been obtained. The photoluminescence spectrum of the(GaAs)$_{1-x}$(ZnSe)$_x$ (0 $\le x\le$ 0.80) films exhibits a narrow peak (against the background of the broad luminescence band) with a maximum in the luminescence intensity at a photon energy of 2.67 eV due to the presence of Zn–Se bonds in the structure (ZnSe is covalently bonded to the tetrahedral lattice of the GaAs matrix). It has been shown that the direct branch of the current-voltage characteristics of the structures under investigation is described by an exponential dependence $I=I_0\exp(qV/ckT)$ at low voltages ($V >$ 0.3 V) and by a power-law dependence $I\sim V^\alpha$ with exponents $\alpha$ = 4 at $V$ = 0.4–0.8 V, $\alpha$ = 2 at $V$ = 0.8–1.4 V, and $\alpha$ = 1.5 at $V >$ 2 V. The experimental results have been explained in the framework of the double-injection model for the $n$–$p$–$p^+$ structure under the condition that the concentration distribution of nonequilibrium charge carriers has a minimum.
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