Regularly arranged indium islands on glass/molybdenum substrates upon femtosecond laser and physical vapor deposition processing

Abstract

A bottom-up approach is presented for the production of arrays of indium islands on a molybdenum layer on glass, which can serve as micro-sized precursors for indium compounds such as copper-indium-gallium-diselenide used in photovoltaics. Femtosecond laser ablation of glass and a subsequent deposition of a molybdenum film or direct laser processing of the molybdenum film both allow the preferential nucleation and growth of indium islands at the predefined locations in a following indium-based physical vapor deposition (PVD) process. A proper choice of laser and deposition parameters ensures the controlled growth of indium islands exclusively at the laser ablated spots. Based on a statistical analysis, these results are compared to the non-structured molybdenum surface, leading to randomly grown indium islands after PVD.

Concentrating light in Cu(In,Ga)Se2 solar cells

“…The CISe micro absorber shown here was obtained in a sequential process from In droplets, which were over-coated with Cu and subsequently selenized. For details regarding the preparation of the local In droplets see [14]. The locally grown absorber reveals a cratered structure with a halo surrounding the central absorber core.…”

Growth of crystalline semiconductor structures on amorphous substrates for photovoltaic applications

“…Proof‐of‐principle studies on CIGSe micro islands prepared by lithography from closed films yielded absolute efficiency enhancements of up to 5% under concentrated illumination . Recently, we proposed a bottom‐up approach for the direct growth of such micro‐absorbers using indium islands as precursors . The preparation of semiconductor micro‐ and nanostructures from metallic In precursors has previously been demonstrated in the case of InP nano rods , and single crystalline InP microstructures grown on amorphous substrates by templated growth from the liquid phase .…”

“…By local roughening of the molybdenum/glass substrate prior to the deposition of In by fs laser pulses, preferential nucleation sites can be created, so that the islands can be arranged in a well‐defined manner, such as regular arrays . When the spacing of arrays of fs laser roughened spots is in the range of the intrinsic islands spacing or lower, interstitial island growth is completely suppressed.…”

“…Laser‐based substrate patterning was carried out at ambient atmosphere by a pulsed Ti:sapphire fs‐laser (Femtolasers, Compact Pro) with a center wavelength of 790 nm, a pulse duration of 30 fs, and a maximum repetition rate of 1 kHz. 20 pulses were applied at each spot with an energy of 340 μJ and a fluence of 2.8 J/cm² (for more details, refer to reference ).…”

Thin-film micro-concentrator solar cells

“…A metallic indium precursor was deposited by PVD onto Mo substrates, which were pre-structured by femtosecond laser pulses [47,48]. This site-selective modification of the Mo surface [49] promoted the localized deposition of In and thus created an easily tunable arrangement of nucleation sites [46][47][48], as schematized in figure 6(a). The In islands were subsequently coated by Cu and converted into CISe by a selenization process, after which excess Cu-Se was removed by a KCN etching step.…”