Effect of tellurium deposition rate on the properties of Cu-In-Te based thin films and solar cells

摘要

To investigate the effects of tellurium (Te) deposition rate on the properties of Cu-In-Te based thin films (Cu/In =0.30-0.31), the films were grown on both bare and Mo-coated soda-lime glass substrates at 200 C by co-evaporation using a molecular beam epitaxy system. The microstructural properties were examined by means of scanning electron microscopy and X-ray diffraction. The crystalline quality of the films was improved with increase in the deposition rate of Te, and exhibited a single CuIn_3Te_5 phase with a highly preferred (1 1 2) orientation. Te-deficient film (Te/(Cu + In) = 1.07) grown with a low Te deposition rate showed a narrow bandgap of 0.99 eV at room temperature. The solar cell performance was affected by the deposition rate of Te. The best solar cell fabricated using CuIn_3Te_5 thin films grown with the highest deposition rate of Te (2.6 nm/s) yielded a total area (0.50 cm~2) efficiency of 4.4% (Voc = 309 mV, Jsc=28.0 mA/cm~2, and FF=0.509) without light soaking.