Implantation line & femtosecond laser
Responsible scientist: José Olivares Villegas
This line is placed at the −20º port of the second switching magnet, connected to the 0 port of the accelerator. This station allows performing homogeneous irradiation over large areas, up to 100 mm × 100 mm, even for the most extreme case of 10 MeV H+, thanks to a fast electrostatic beam raster (operating at kHz) provided by HVE. The irradiation chamber is electrically isolated, and designed for ultra-high vacuum conditions. The load-lock is compatible with the use of 3-inch wafers. The fluence is controlled by measuring the beam current in two different ways. On the one hand, the system incorporates a Faraday cup located before the vacuum valve. On the other hand, a combination of four Faraday cups, located after the vacuum valve and immediately before the irradiation chamber can be used. The chamber contains a cryostat/furnace that allows modifying the heating and cooling ramps in order to control the sample temperature during the irradiations. The temperature can be varied from −196ºC (liquid nitrogen cooling) up to 600ºC. The sample holder can be tilted in the 90º range with respect to the beam axis, allowing the in-situ characterization. This holder is made of copper to favour a uniform temperature gradient.
Additionally, the beam line is provided with an InfraTec VarioCAM thermographic camera, to monitor the temperature distribution during the irradiation. Several optical techniques for in-situ measurements are available, including reflectance, transmittance and ellipsometry, all in the broad range VIS-UV.
Recently, a large macro-external beam has been developed by means of using thin foils in apertures engraved at the back flange of the irradiation chamber.
This set-up is capable to generate a broad beam (30 mm × 1 mm) of heavy ions into the air.
Quite remarkably, this beam line was designed to allow simultaneous irradiation with a femtosecond pulsed laser (Spectra Physics Solstice ACE model, regenerative amplifier). The laser delivers 100 fs pulses of 6mJ/pulse, at 1 kHz repetition rate and 800 nm wavelength. An additional external wavelength conversion module is available to generate pulses at 400 or 266 nm wavelengths, as desired. The laser beam is directed towards the implantation chamber through a silica window.