Thermodynamic study of the ternary system gallium‐arsenic‐bismuth

Abstract

Binary thermodynamic data, successfully used for phase diagram calculations of binary system Ga‐As, Ga‐Bi and As‐Bi were used for prediction of phase equilibria in ternary Ga‐As‐Bi system. The parameters for the thermodynamic models of the constituent binary systems and those for the Ga‐As‐Bi system are optimized in this study using data on phase equilibria and data on the different alloys available in the literature and calculated in the present work. The implications of the phase data for solution epitaxy are discussed. The liquidus surface and isothermal section were calculated. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Annealing-induced precipitate formation behavior in MOVPE-grown GaAs1−xBixexplored by atom probe tomography and HAADF-STEM

“…Comparison of the compositions of the phases in the particle with computed Bi-Ga-As ternary and Bi-Ga binary phase diagrams provides an explanation for the intra-particle phase separation. According to sections of the Ga-As-Bi ternary phase diagram system [2], at 750 °C bulk material with the composition deduced for the entire particle (that is, within the 12% iso-concentration surface), would, at equilibrium, consist of nearly pure zinc-blende GaAs and a singlephase Bi-Ga liquid solution of composition ∼50 at% Ga. The Bi-Ga binary phase diagram, reproduced [51] and annotated in figure 12, indicates that a liquid with this Ga:Bi ratio would be a single-phase solution at the annealing temperature of 800 °C and persist on cooling to about 250 °C.…”

“…The possibilities for development of new and improved longwavelength optoelectronic devices that are offered by the GaAs 1−x Bi x alloy system have driven renewed study of the electronic structure, the physical properties, and the phase formation of epitaxial materials in this series of compound semiconductor materials system. This research has addressed, among other questions, the considerable challenges of fabricating homogeneous thin films of controlled composition that are presented by the near insolubility (x≈5×10 −5 ) of Bi in bulk GaAs at any temperature [1,2]. Through understanding and manipulating the physical and chemical processes that occur during both molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) [3][4][5][6][7] it is now possible to fabricate single-phase epitaxial films with thicknesses ranging from a few to a few hundred nanometers and homogeneous Bi concentrations up to as high as x≈0.07 [5] and x≈0.22 [8] for MOVPE and MBE-deposited materials, respectively.…”

Axial GaAs/Ga(As, Bi) nanowire heterostructures

“…According to the bulk Ga-Bi phase diagram, Ga and Bi form a homogeneous mixture for all Bi concentrations above the Bi melting point (271.4 • C) [30,31]. Thus, the Ga-Bi droplet should be a homogeneous liquid mixture for all As 2 exposure temperatures, with the possible exception of the lowest temperature of 270 • C. The addition of As 2 is expected to precipitate a GaAs-rich solid [32,33].…”