Nanostructured surfaces
Optical and photoelectric properties of the CdTe: Cu layer
Maliarska I. V., Ilnitsky R.V., Naidych B.P., Matkivskiy O., Zapukhlyak Z.R., Katanova L.O.
Vasyl Stefanyk Precarpathian National University, Shevchenko Str., 57, 76018, Ivano-Frankivsk, Ukraine

Semiconductor thin-film solar cells with a multilayer structure are increasingly popular for obtaining renewable energy from solar radiation. The efficiency of solar cells can be significantly increased by controlled modification of the heterostructure [1].
Cadmium telluride with complex parameters such as an optimal band gap (1.45 eV), high absorption coefficient (105 cm-1) and p-type of conductivity has proven to be an excellent material of the light absorber layer for photovoltaic applications. The high efficiency up to 21% of multilayer solar cells has been recorded based on CdTe / CdS [2]. CdTe is a direct-band semiconductor that can have both n-type and p-type conductivity, depending on the use of appropriate alloying impurities [3]. Therefore, controlled doping of these materials with p and n-type of carriers we can significantly improve the efficiency of PV-modules based on them.
The deposition technology is developed and the influence of copper impurity concentration on the optical properties of CdTe thin films is studied. To obtain thin films, the method of open evaporation in vacuum is used, which ensures the purity of the film due to the high vacuum [4]. In [1] show that the band gap decreases slightly with increasing concentration of the alloying impurity (Eg1 = 1.50 eV (for 1% Cu), Eg2 = 1.48 eV (for 2% Cu), Eg3 = 1.45 eV (for 3% Cu)), however, a high absorption coefficient is observed in the film. Therefore, thin CdTe films doped with 3% Cu will be suitable for the p-layer of a highly efficient p-n solar cell, based on CdTe.

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