Direct patterning of nanostructures by field-induced deposition from a scanning tunneling microscope tip

Abstract

The process of local-field-induced deposition on a surface facing a scanning tunneling microscope (STM) tip has been investigated for several tip-sample systems. Applying negative voltage pulses, atoms can be transferred from the STM tip to the surface and, for example, platinum dots and lines have been drawn on gold or silicon samples by this technique. In this latter case, a discussion is proposed on growth mechanisms involved in field-induced deposition processes on the basis of growth kinetics studies. When positive voltage pulses are applied to a silicon sample placed in tunneling conditions with a STM tip, silicon nanofeatures are elaborated on the substrate surface by field-enhanced surface diffusion of silicon atoms.

Nanoscale Fabrication by Nonconventional Approaches

“…Material deposition has also been observed at short pulses on the order of 10 ns, but a small change in the amount of materials deposited is observed with a pulse duration larger than 10 ms, which may imply the existence of a sort of saturation mechanism. Houel et al 17 also reported that the dot diameter increases slightly with the set current and pulse duration for the range considered. Moreover, the number of pulses has been found to have no influence on the dot volume deposition as long as the dot has been successfully deposited in the first few pulses.…”

“…There is a threshold voltage for the direct deposition. As indicated by Mamin et al 16 and Houel et al, 17 the threshold voltage, normally a few volts, is mainly influenced by the materials of tip and target, the distance of the tip-target gap, the tip-target configuration, and polarity. Mamin et al 16 also discovered that a gold dot previously deposited can be removed by a subsequent pulse on the same location.…”

“…Houel et al 17 used Pt STM tips with a radius of 50 nm to deposit dots and lines on n-type Si substrates. Dots were deposited by using sequential pulses with the tip maintained at a fixed position on the target, while the lines were constructed by sequential dots, in which each dot is connected with the neighboring dots by a slight overlap.…”

Quasi-one-dimensional quantum well on Si(100) surface crafted by using scanning tunneling microscopy tip

“…Depositing metal nanodots from the STM tip has been extensively studied for fabricating electrodes and circuits for electronic devices. [9][10][11][12][13][14][15] Most previous research used field-induced fabrication of dots where, between the tip and the sample, a voltage pulse of more than a few volts was applied 9-14 or the bias voltage was ramped to induce a point contact. 15 These methods yielded dots with lateral diameters ranging from several to hundreds of nanometers.…”

“…It should be noted that the nanodots created by the point contacts were much smaller than those fabricated using high voltages. [9][10][11][12][13][14] The distance of the approaching tip necessary for making the point contact was determined by monitoring the tunneling current. Figure 1͑b͒ shows tunneling current as a function of the z-piezo displacement ͑I-Z curve͒ for two different tips ͑curves A and B͒ when the tip apex atom transfer has occurred.…”