Nucleation of Cu₂Te layer by a closed space sublimation method toward the growth of Te based chalcopyrite

Nucleation of Cu-Te layers was performed by the closed space sublimation method using various source materials, source temperatures, and Si substrates with different surface orientations. The objective was to produce nuclei layers with high quality for use as nucleation centers for CuGaTe₂. The grown samples were evaluated by x-ray diffraction and scanning electron microscopy. Cu₂Te deposits were obtained using either a CuTe or Cu₂Te source, but the latter gave a higher area coverage of Cu₂Te nuclei. Highly oriented nuclei were obtained when they were grown on Si (001) at a source temperature of 640 °C and substrate temperature of 590 °C. When the source temperature was raised to 750 °C and the corresponding substrate temperature was 700 °C, nonuniform but highly oriented nuclei were obtained. Both nuclei layers exhibited a strong preference for (0001) orientation. The crystallographic features of the Cu₂Te nuclei formed on Si (111) were similar to those of the Cu₂Te nuclei formed on Si (001).