Characterization of the phases and morphology in synthesizing Cu_2-xSe and CuSe films

ABSTRACT

Copper Selenides are important semiconductor materials with excellent performance. Cu_2-xSe and CuSe films were synthesized by spin-coating and chemical co-reduction method. The phases of product films were analyzed by X-ray diffraction (XRD) and the morphology was characterized by scanning electron microscopy (SEM), and the compositions of products were analyzed by energy dispersive spectroscopy (EDS). The surface resistance of the product film was measured using a four-probe resistance instrument. When Copper chloride was chosen as copper source, the products contain Cu_2-xSe, CuSe and a small amount of NaCl. When the reacting temperature is below 180 °C, the XRD intensity of impurity phase NaCl is obviously increased, while it is easier to produce Cu₂Se film at 200 or 220 °C. The sample obtained at 160 °C for 20 h consists of about 0.3 ∼ 0.5 µm particles, while the sample obtained at 220 °C shows about 2 ∼ 4 µm flake crystals; When the copper nitrate is used as a raw material, the XRD peaks of the product obtained at 200 °C for 20 h are much high and sharp, the phases obtained are mainly CuSe. The sample obtained at 200 °C consists of hexagonal flaky crystals with about 2 ∼ 3 µm diameters, while it consists of particles with about 0.3 ∼ 0.5 µm diameters for the sample obtained at 220 °C. In addition, the longer reaction time is conducive to the copper selenide formation, for example the single phase CuSe film can be obtained at 220 °C. The average resistivity of Cu-Se films synthesized at 200 °C for 20 h is 2.12E-3 Ω·cm.

Keywords:

• Copper selenide
• spin-coating
• chemical co-reduction
• Cu_2-xSe
• CuSe

Funding

This work was financially supported by the National Natural Science Foundation of China (No. 51272140).