Whereas antimony telluride based compound materials have been demonstrated to be suitable for phase change memory devices,^[1] among other applications, and are well suited to be fabricated via an electrochemical route, the ability to electrodeposit high quality thin films of these materials requires a good understanding of the nucleation and growth behavior that defines the initial stages of growth of these films.^[2-4] Although electrochemical nucleation has been studied for decades,^[5] little attention has been paid to the behavior of codeposition systems, where two or more materials are deposited simultaneously from a single electrolyte bath. In this study, the nucleation of Sb-Te compound is studied on gold and glassy carbon electrodes, to determine how the nucleation behavior of each element contributes to that of the overall system. Additionally, the effect of applied potential and electrolyte concentrations on the nucleation behavior and deposit composition is studied.

Cyclic voltammetry coupled with quartz crystal microbalance measurements are used to extensively study the deposition processes that occur during compound electrodeposition. It is seen that deposited Te is further reduced to a soluble species near the potentials required to deposit Sb, however the presence of Sb in the deposited film seems to hinder the further reduction to a soluble species, enabling compound film growth (figure 1). Additionally, the free energy released by compound formation allows the compound to be formed at potentials positive to those normally required for Sb deposition. Chronoamperometry, along with TEM-EDS analysis of the composition gradient of individual nucleation sites will be presented and discussed in conjunction with the CVs to understand the nucleation and growth of binary Sb-Te compounds.

REFERENCES

1. Raoux, S.; Wuttig, M., Phase Change Materials: Science and Applications. New York : Springer Dec. 2008: 2008.

2. Huang, Q.; Kellock, A. J.; Raoux, S., Electrodeposition of SbTe Phase-Change Alloys. Journal of The Electrochemical Society 2008, 155(2), D104-D109.

3. Catrangiu, A. S.; Sin, I.; Prioteasa, P.; Cotarta, A.; Cojocaru, A.; Anicai, L.; Visan, T., Studies of antimony telluride and copper telluride films electrodeposition from choline chloride containing ionic liquids. Thin Solid Films 2016, 611, 88-100.

4. Jung, H.; Myung, N. V., Electrodeposition of antimony telluride thin films from acidic nitrate-tartrate baths. Electrochimica Acta 2011, 56(16), 5611-5615.

5. Gunawardena, G.; Hills, G.; Montenegro, I.; Scharifker, B., Electrochemical nucleation. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 1982, 138 (2), 225-239.