Cu(In, Ga)Se2 thin films processed by co-evaporation and their application into solar cells

J. Sastré-Hernández, M. E. Calixto, M. Tufiño-Velázquez, G. Contreras-Puente, A. Morales-Acevedo, G. Casados-Cruz, M. A. Hernández-Pérez, M. L. Albor-Aguilera, R. Mendoza-Pérez

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7 Scopus citations

Abstract

Polycrystalline Cu(In, Ga)Se2 (CIGS) solar cells are attractive because low cost techniques can be used to obtain high efficiency thin film photovoltaic devices. Several research groups around the world have developed CIGS/CdS solar cells with efficiencies larger than 15% [1] using evaporation, making it an attractive and reliable technique for thin film deposition. Our PVD system is provided with MBE-type Knudsen cells to deposit CIGS thin films on glass/Molibdenum (Mo) substrates. The deposition conditions for each metal source have been established by doing a deposition profile of temperature data vs. growth rate by co-evaporation to obtain CIGS thin film for solar cells. Characterization of the co-evaporated CIGS thin films was performed by X-ray diffraction (X-RD), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) techniques. Good quality polycrystalline films were obtained as shown by X-RD patterns. SEM micrographs show films having a very uniform appearance with large grain sizes (~1 μm). Photoluminescence (PL) studies on CIGS samples with different Ga and Cu concentrations (Ga/Ga+In) = 0.25 and 0.34 and (Cu/In+Ga) = 0.83, 0.88 and 0.94) have been performed. The EDS results have shown that is possible to control very precisely the CIGS thin film composition using these Knudsen cells. Film thicknesses of ~3-4 μm, were measured with an Ambios profilemeter XP 100 stylus type. A conversion efficiency of 10.9 % has been achieved for solar cells made from the co-evaporated absorbers.

Original languageEnglish
Pages (from-to)441-445
Number of pages5
JournalRevista Mexicana de Fisica
Volume57
Issue number5
StatePublished - 2011

Keywords

  • Co-evaporation
  • Solar cells
  • Thin films

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