Growth of (GaAs)1 − x (ZnSe) x solid solution films and investigation of their structural and some photoelectric properties

Abstract

Single-crystal films of the substitutional solid solution (GaAs)1 − x(ZnSe)x (0 ≤ x ≤ 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 ≤ x ≤ 0.80) heterostructures prepared have been investigated. The lattice parameters of the film af = 5.6544 A and the substrate as = 5.6465 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 ≤ x ≤ 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 = I0exp(qV/ckT) at low voltages (V > 0.3 V) and by a power-law dependence I ∼ Vα with exponents α = 4 at V = 0.4–0.8 V, α = 2 at V = 0.8–1.4 V, and α = 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.