Nanostructured Ultrafast Silicon-Tip Optical Field-Emitter Arrays

作者：Swanwick Michael E; Keathley Philip D; Fallahi Arya; Krogen Peter R; Laurent Guillaume; Moses Jeffrey; Kaertner Franz X; Velasquez Garcia Luis F^*

来源：Nano Letters, 2014, 14(9): 5035-5043.

DOI：10.1021/nl501589j

• Strong-field photoemission
• ultrafast optics
• field emission
• nanosharp
• silicon emitters
• field emitter array

Femtosecond ultrabright electron sources with spatially structured emission are an enabling technology for free-electron lasers, compact coherent X-ray sources, electron diffractive imaging, and attosecond science. In this work, we report the design, modeling, fabrication, and experimental characterization of a novel ultrafast optical field emission cathode comprised of a large (>100 000 tips), dense (4.6 million tips.cm(-2)), and highly uniform (<1 nm tip radius deviation) array of nanosharp high-aspect-ratio silicon columns. Such field emitters offer an attractive alternative to UV photocathodes while providing a direct means of structuring the emitted electron beam. Detailed measurements and simulations show pC electron bunches can be generated in the multiphoton and tunneling regime within a single optical cycle, enabling significant advances in electron diffractive imaging and coherent X-ray sources on a subfemtosecond time scale, not possible before. At high charge emission yields, a slow rollover in charge is explained as a combination of the onset of tunneling emission and the formation of a virtual cathode.

• 出版日期2014-9
• 单位MIT