## 1 Introduction  
Zinc-based semiconductor crystals (zinc oxide, zinc sulfide, zinc selenide, etc.) have received considerable attention because the energy band gap level is suitable for developing a novel optical material. The energy band gap of zinc telluride is ca. 2.26 eV that equals to the spectrum range of around 550 nm in wavelength. Hence, zinc telluride crystals have a potential application in light emitting diodes and photovoltaic cells. It has been reported that the crystalline zinc telluride thin films were able to be synthesized using some crystal growing processes, such as vacuum evaporation [1, 2], sputter deposition [3], CVD [4], and electrochemical growth from a non-aqueous solvent [5, 6, 7, 8, 9] and from an aqueous solution [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23]. The electrochemical growing technique from an aqueous solvent has an excellent cost-performance in comparison to the other processes and it enables us to coat a conventional wide panel with a practically applicable surface appearance. Zinc and tellurium are known to be not so harmful in comparison to some elements, such as arsenic, cadmium, lead, and selenium. [PERSON] et al. reported the electrodeposition of zinc telluride (ZnTe) thin films on FTO substrates from an acid chloride bath [12]. They revealed that the band gap and sheet resistance of the post-annealed samples increased by up to 2.31 eV and 815 k\(\Omega\)/sq., respectively, by increasing the annealing temperature from 623 K to 672 K. [PERSON] et al. reported that ZnTe thin films can be prepared by using a potentiostatic electrodeposition technique from a simple sulfuric acid bath [15]. They found that the band gap of as-deposited ZnTe thin films was approximately 1.9 eV, while samples annealed at 623 K for 1 h exhibited 2.25 eV, which was in good agreement with the optical bandgap values of single-crystal ZnTe. [PERSON] et al. also reported the electrodeposition of ZnTe thin films on stainless steel sheets from a simple sulfuric acid bath [16]. They discovered that the band gap of as-deposited ZnTe thin films was 2.1-2.3 eV, and the resistivity was greater than 10\({}^{7}\)\(\Omega\)-m, while samples annealed at 623 K for 15 min showed p-type conductivity. [PERSON] et al. reported that ZnTe thin films could be electrodeposited on FTO substrates from an acid chloride bath [20]. They revealed that the band gap of as-deposited ZnTe thin films was approximately 2.19 eV, whereas samples annealed at 623 K for 20 min exhibited a smaller band gap value.  
Thus, the post-annealing process improves the semiconductor performance of electrodeposited ZnTe films. However, the morphology of ZnTe films that are electrodeposited from simple acidic aqueous solutions, such as sulfuric acid or hydrochloric acid, exhibits a coarse nodule-like structure that is undesirable for opto-electronic devices. The coarse nodule-like structure seems to be induced by the preferential electrodeposition of tellurium, which is electrochemically more noble (positive direction) than zinc. To inhibit the preferential electrodeposition of tellurium, the addition of complexing agents, such as organic acids, may be effective. [PERSON] et al. reported that the morphology of ZnTe films electrodeposited from an aqueous solution containing citric acid exhibited a smooth and uniform surface appearance with fine crystals [23]. Hence, in this work, we studied the effect of the post-annealing process on the crystallization of ZnTe films and elucidated the semiconductive properties of films electrodeposited from a citric acid bath. Furthermore, a zinc telluride nanowire structure was also demonstrated using a template synthesis technique to confirm the uniform electrodeposition from the citric acid bath.