Systematic investigation of self-absorption and conversion efficiency of 6.7 nm extreme ultraviolet sources

Takamitsu Otsuka, Deirdre Kilbane, Takeshi Higashiguchi, Noboru Yugami, Toyohiko Yatagai, Weihua Jiang, Akira Endo, Padraig Dunne, Gerry O'Sullivan
2010 Applied Physics Letters  
We have demonstrated rare-earth plasma extreme ultraviolet sources at 6.7 nm to investigate the spectral behavior and the conversion efficiencies to different laser wavelength and the initial target densities. The conversion efficiency was maximized to be 0.9% at laser intensity of 7 × 10 12 W/cm 2 at its wavelength of 1064 nm, which is attributed to the minimum self-absorption effect by use of the low initial density target, together with the narrow spectrum. It is important to use a low
more » ... l density target and to produce low electron density plasmas for efficient EUV sources using the high-Z targets.
doi:10.1063/1.3526383 fatcat:zzhwhxgmunb4nhcfev773z5m6u