Electrochemical Liquid-Liquid-Solid Deposition of Crystalline Gallium Antimonide

Abstract

Direct electrodeposition of phase-pure crystalline gallium antimonide (GaSb) films has been achieved at low processing temperatures from an aqueous electrolyte. A liquid gallium electrode was used to drive the electroreduction of Sb 2 O 3 dissolved in 0.6 M NaOH. The quality and purity of the resultant films produced depended strongly on the chosen conditions, including temperature, time, and concentration of dissolved Sb 2 O 3. Under select conditions, the direct production of polycrystalline films of GaSb was possible. Raman spectroscopy, powder X-ray diffraction, selected area electron diffraction, scanning electron microscopy, and transmission electron microscopy were separately used to analyze the identity and crystallinity of the electrodeposited films. The cumulative data showed that this electrodeposition process followed the features common both to conventional electrodeposition and melt crystal growth. Accordingly, this electrodeposition process could not be categorized as electrodeposition followed by annealing. Rather, the data implicate this method is akin to a hybrid electrodeposition solution-based crystal growth, where crystalline GaSb films could be grown up to thicknesses of 1 µm in 60 min.

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

“…This work represents the fourth distinct system where a crystalline binary material is synthesized by a sequential electrodeposition of a group V element and a subsequent alloying reaction. In accord with the prior observations for InAs, GaAs, and GaSb, three general themes were clear: (1) the reaction critically hinged on the removal of the surface oxide, (2) accumulation of Sb 0 occurs when the deposition outpaces the alloying reaction with In 0 , and (3) Sb 0 can be selectively removed at large overpotentials to yield thicker and homogeneous InSb films. These points are summarized in Scheme and are discussed below.…”

“…A specific challenge in electrodeposition strategies is the ability to prepare semiconductor films rapidly that are simultaneously thick and crystalline as-prepared. Our group has started to explore the concept of combining an alloying reaction with freshly electrodeposited species to form new phases and/or compounds. − The appeal of this approach is that it synergizes the synthetic power of metallurgical reactions with the control over heterogeneous reaction rates inherent in electrochemical reactions. Although prevalent in the context of rechargeable batteries, amalgam formation, , and with some analogy to the concept of underpotential deposition, the intentional reaction of an electrodeposited species with the underlying metal electrode has not been extensively explored for the purpose of producing technologically relevant III–V semiconductors.…”

“…Indium antimonide (InSb) is one such target material, with extremely high carrier mobilities and a small bandgap suitable for sensing (e.g., photodetectors) and energy (lattice matched substrates for CdTe photovoltaics, , IR absorbers in thermophotovoltaics) technologies. Building off our prior demonstrations of hybrid electrodeposition–alloying reaction syntheses of crystalline InAs, GaAs, and GaSb, − we are interested in the synthesis of InSb as a further test of the electrochemically controlled alloy reaction concept because InSb has a negative free energy of formation at room temperature (−25.3 kJ mol –1 at T = 300 K) and Sb can be electrodeposited from aqueous solutions. Therefore, a simple alloying reaction between zero-valent In and Sb to form InSb should be spontaneous and strongly favored at room temperature (eq ) when Sb is electrodeposited on indium electrodes. Herein, this report presents a series of spectroelectrochemical experiments where the chemistry at an indium electrode interface is monitored by Raman spectroscopy to identify any evidence for eq .…”

Electrochemical Liquid Phase Epitaxy (ec-LPE): A New Methodology for the Synthesis of Crystalline Group IV Semiconductor Epifilms

“…We previously demonstrated the concept that bulk liquid metals can simultaneously facilitate the electroreduction of oxidized semiconductor precursors and the formation of zerovalent semiconductor nano- and microcrystals, − affording a pathway to simplify preparation of crystalline semiconductors. However, to date, an analogous process for macroscopic, crystalline semiconductor films has never been conceived.…”

Low-Cost Approaches to III–V Semiconductor Growth for Photovoltaic Applications

“…These growth systems must have the potential for production at scale and preferably be compatible with techniques that dramatically reduce substrate costs, such as those described above. Some alternative approaches to III–V growth propose to dramatically lower device costs by, for example, reducing materials use (nanowire solar cells grown on-wafer), − utilizing low-purity precursors for growth on nonepitaxial substrates (electrochemical liquid–liquid–solid growth), − or eliminating the growth substrate entirely (aerotaxy). − While each of these approaches shows promise, they are not compatible with conventional PV architectures and require substantial demonstration before they can be considered as replacements for MOVPE or for planar device architectures.…”