Preparation of self-supporting Au thin films on perforated substrate by releasing from water-soluble sacrificial layer

A self-supporting thin film is useful as a target material for laser-driven ion acceleration experiments. In this study, 100-nm-thick sputtered gold (Au) thin films were released from substrates using water-soluble sacrificial layers, and the released films were subsequently scooped up on perforated substrates. Au thin films were deposited by DC plasma sputtering on the sacrificial layers. In the releasing test, sodium chloride (NaCl) was shown to be most suitable as a sacrificial layer for Au thin films. In addition, sputtered Au thin films with thicknesses of 50 and 150 nm were deposited onto NaCl sacrificial layers, released on water, and scooped up on perforated substrates. Self-supporting Au thin films were obtained for all film thicknesses, but wrinkles and cracks appeared in the 50 nm film.