The use of silver tips in scanning tunneling microscopy

We describe a reliable fabrication procedure of silver tips for scanning tunneling microscope (STM) induced luminescence experiments. The tip was first etched electrochemically to yield a sharp cone shape using selected electrolyte solutions and then sputter cleaned in ultrahigh vacuum to remove surface oxidation. The tip status, in particular the tip induced plasmon mode and its emission intensity, can be further tuned through field emission and voltage pulse. The quality of silver tips thus fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging "color" photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.

Section: Introductionmentioning

confidence: 99%

Fabrication of silver tips for scanning tunneling microscope induced luminescence

Zhang

Gao

Chen

et al. 2011

“…Among various methods explored, electrochemical etching [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] proved to be an inexpensive, efficient, and reliable way to fabricate extremely sharp tips. Other reported techniques include cutting, 23,24 grinding, [1][2][3][4][5][6]25 pulling, 19,[26][27][28][29][30] beam deposition, [31][32][33][34] ion milling, [35][36][37][38][39] and others. For electrochemical etching, recent advances in tip fabrication came in the form of reverse biasing after "drop-off," 21 in 2002 and "dynamic electrochemical etching" 40 in 2007.…”

Section: Introductionmentioning

confidence: 99%

Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

Khan

Al-Falih

Zhang

et al. 2012

Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as "dynamic electrochemical etching" and reverse biasing after "drop-off" are utilized, and "two-step dynamic electrochemical etching" is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc "drop-off" technique is reduced to ∼36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel "dynamic electrochemical etching." Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes.

“…7 In this note we describe a new single-step electrochemical etching technique to produce silver tips with a welldefined geometry and an apex radius of 50-100 nm. 7 In this note we describe a new single-step electrochemical etching technique to produce silver tips with a welldefined geometry and an apex radius of 50-100 nm.…”

mentioning

confidence: 99%

New etching procedure for silver scanning tunneling microscopy tips

Dickmann

Demming

Jersch

1996

Due to its physical and chemical features silver is a promising material for scanning tunneling microscopy (STM) tips in the field of nanostructuring by a laser/STM combination. This nanostructuring is archived by field enhancement of optical radiation by a factor of up to 103 in the near field between a STM tip and a substrate. The magnitude of the field enchantment depends on the geometry and material of the utilized tip. State of the art procedures of processing silver tips cannot be applied to this application due to insufficient quality and reproducibility, respectively. We have developed a new simple single-step etching procedure for silver tips with a high reproducibility and a tip radius of less than 100 nm. This was realized by electrochemical etching in an ammonia solution and subsequent electronic controlled movement of the tip out of the electrolyte.