Free-Standing Silicon Nanogratings for Extreme UV Rejection

The integration of compact, sturdy, and lightweight sensors into satellites for measurement of low-density plasmas has been hindered by their inherent sensitivity to extreme UV photons. Silicon nanograting structures that reject extreme UV light while allowing particles to pass through have improved on previous gold gratings in terms of stability and ease of fabrication, but comparable UV rejection was not attained since Si acts as a plasmonic material in the extreme UV. In order to alter the plasmonic properties of the structure, atomic layer deposition technology was utilized during fabrication, and extreme UV transmission comparable to previous results was achieved. This work reports the fabrication and measurement of coated, free-standing Si nanogratings created over a large area using nanoimprint lithography. With reduction in defect density, these structures could outperform current gold gratings as UV filters in space-based mass spectrometry systems.