Low temperature growth and properties of Cu-In-Te based thin films for narrow bandgap solar cells

Characterization of CuInTe2 thin film synthesized by three source co-evaporation technique

CuInTe2 thin films synthesized by graphite box annealing of In/Cu/Te stacked elemental layers

Copper–indium–telluride films were electrochemically deposited from solutions containing CuCl 2 , InCl 3 , TeO 2 and HCl. Although a flat and smooth film with closely stoichiometric composition was deposited at −660 mV vs. Ag/AgCl at 303 K from a solution of 2.5×10 −4 mol dm −3 CuCl 2 , 1.0×10 −2 mol dm −3 InCl 3 , 5.0×10 −4 mol dm −3 TeO 2 and 0.1 mol dm −3 HCl, a polycrystalline CuInTe 2 film was not obtained. Increasing the temperature from 303 to 363 K allowed the deposition at lower overpotential of a polycrystalline CuInTe 2 film with closely stoichiometric composition and increased indium content. The band gap of the polycrystalline CuInTe 2 film electrodeposited at 363 K at −660 mV was 0.98 eV.

Electrodeposition of CuInTe2 film from an acidic solution

The effects of substrate temperature (Tsub) and film thickness (dCIT) on the properties of CuIn3Te5 thin films and solar cells were investigated. CuIn3Te5 thin films (dCIT = 1.8–4.0 μm) were grown on both bare and Mo-coated soda-lime glass substrates at Tsub of 250–400 °C by single-step co-evaporation using a molecular beam epitaxy system. The microstructural properties were examined using scanning electron microscopy and x-ray diffraction. Well-developed (112)-oriented CuIn3Te5 grains were obtained by increasing the dCIT for Tsub of 250 °C. Cathodoluminescence analysis and temperature-dependent Hall measurements indicate the formation of shallow defect levels in the CuIn3Te5 films grown at higher Tsub. An optimum solar cell fabricated using CuIn3Te5 thin films (Tsub = 250 °C, and dCIT = 4.0 μm) yielded a total area (0.504 cm2) efficiency of 6.28%. Recombination mechanisms in the CdS/CuIn3Te5 thin-film solar cells are discussed on the basis of the temperature-dependent electrical properties of the films a...

Effects of substrate temperature and film thickness on properties of CuIn3Te5 thin films and solar cells

The CuInTe2 thin films were prepared by thermal vacuum evaporation of the bulk compound. The structural and optical properties in the temperature range 300–47 K of thin films grown on glass substrates and annealed in vacuum were studied. The films were investigated by X-ray diffraction and electron microscope techniques. The calculated lattice constants for CuInTe2 powder were found to bea=0.619 nm andc −1,234 nm. From the reflection and transmission data, the optical constants, refractive indexn, absorption index,k, and the absorption coefficient, α, werw computed. The optical energy gap was determined for CuInTe2 thin films heat treated at different temparatures for different periods of time. It was found thatE
g increases with both increasing temperature and time of annealing.

T. A. Hendia

Papers

Effect of heat treatment on the structural and optical properties of CuInTe2 thin films