Growing the solid solution of molekular substitution (GaAs)1-z(ZnSe)z

Abstract

Epitaxial layers of semiconductor solid solutions of molecular substitution (GaAs)1-z(ZnSe)z (0 < z < 0.80) with a smoothly (but not monotonously) varying composition were obtained from the liquid phase on monocrystal GaAs (100) substrates. The solubility of gallium arsenide and zinc selenide in tin and the phase diagrams of binary systems Ga-Sn, As-Sn, Zn-Sn and Sn-Se indicate that binary compounds in the tin solvent at temperatures of 650–750°C, below the melting point of the corresponding materials, are not in the form of individual atoms of gallium, arsenic, zinc and selenium, but in the form of molecules of gallium arsenide and zinc selenide. Moreover, in the temperature range 650-750°C, the solubility of GaAs in tin varies from ∼ 2.6 to ∼ 5.5 mol%, and ZnSe - from ∼ 0.2 to ∼ 0.35 mol%, the solubility of gallium and zinc is unlimited, and the solubility of arsenic is more than 70 at. %, selenium - more than 5 at.%. It is shown that due to the difference in the valence of gallium and arsenic atoms, the forces of chemical bonds between neighboring Ga and As atoms located in the tetrahedral lattice are not the same. In the tetrahedral lattice, each Ga atom forms 4 bonds with four neighboring As atoms, three of which are formed by the sharing of electrons of neighboring Ga and As atoms, and the fourth one only due to the two valence electrons of the As atom. Apparently, the ionic fraction of the fourth chemical bond is stronger than the other three.