Concerted Electrodeposition and Alloying of Antimony on Indium Electrodes for Selective Formation of Crystalline Indium Antimonide

The direct preparation of crystalline indium antimonide (InSb) by the electrodeposition of antimony (Sb) onto indium (In) working electrodes has been demonstrated. When Sb is electrodeposited from dilute aqueous electrolytes containing dissolved Sb₂O₃, an alloying reaction is possible between Sb and In if any surface oxide films are first thoroughly removed from the electrode. The presented Raman spectra detail the interplay between the formation of crystalline InSb and the accumulation of Sb as either amorphous or crystalline aggregates on the electrode surface as a function of time, temperature, potential, and electrolyte composition. Electron and optical microscopies confirm that under a range of conditions, the preparation of a uniform and phase-pure InSb film is possible. The cumulative results highlight this methodology as a simple yet potent strategy for the synthesis of intermetallic compounds of interest

Eutectic-Bismuth Indium as a Growth Solvent for the Electrochemical Liquid-Liquid-Solid Deposition of Germanium Microwires and Coiled Nanowires

Crystalline germanium (Ge) micro- and nanowires have been grown from aqueous electrolytes through an electrochemical liquid-liquid-solid (ec-LLS) process using eutectic bismuth indium (e-BiIn) alloy as the liquid metal electrode. This alloy represents the first non-Hg or non-Ga containing liquid metal to be used for the growth of a group IV semiconductor crystal below the boiling point of water. The electrochemical stability of e-BiIn in aqueous electrolyte was assessed through cyclic voltammetry, which showed the metal alloy was destabilized either by anodic oxidation at potentials more positive than −1.0 V vs <i>E</i>(Ag/AgCl) or by cathodic reduction of Bi to BiH₃ at potentials more negative than −1.4 V vs <i>E</i>(Ag/AgCl). Within this potential window, ec-LLS produced Ge micro- and nanowires that were evaluated with scanning electron microscopy, high resolution transmission electron microscopy, and selected area electron diffraction. The cumulative analyses showed pronounced crystallinity in the as-prepared Ge microwires and nanowires, with nanowires showing an unexpected coiled morphology. Atom probe tomography data showed some incorporation of In and Bi at 6 and 3 at. %, respectively. The tomography data further demonstrated that the distribution of the metals was not uniform, as In-rich clusters were observed. A high doping character in the as-prepared Ge nanowires was separately confirmed with two-terminal resistivity measurements. In total, this work not only identifies a new liquid metal type that is amenable for ec-LLS but also suggests strongly that the composition of the liquid metal influences the resultant crystal size, shape, and purity