Enhanced performance of an EUV light source (λ=84 nm) using short-pulse excitation of a windowless dielectric barrier discharge in neon

The electrical and optical characteristics of a dielectric barrier discharge (DBD) based neon excimer lamp generating output in the extreme ultraviolet (EUV) spectral range (lambda = 84 nm) have been investigated experimentally. We report a detailed comparison of lamp performance for both pulsed and sinusoidal voltage excitation waveforms, using otherwise identical operating conditions. The results show that pulsed voltage excitation yields a similar to 50% increase in the overall electrical to EUV conversion efficiency compared with sinusoidal waveforms, when operating in the pressure range 500-900 mbar. Pulsed operation allows greater control of parameters associated with the temporal evolution of the EUV pulse shapes (risetime, instantaneous peak power). The Ne DBD based source is also found to be highly monochromatic with respect to its spectral output from the second continuum band at lambda similar to 84 nm (5 nm FWHM). This continuum band dominates the spectral emission over the wavelength range 30-550 nm. Lamp performance; as measured by the overall EUV output energy, electrical to EUV conversion efficiency and spectral purity at lambda similar to 84 nm; improves with increasing gas pressure up to p = 900 mbar.