Rapid Prototyping of Site-Specific Nanocontacts by Electron and Ion Beam Assisted Direct-Write Nanolithography

Abstract

Rapid prototyping of bottom-up nanostructure circuits is demonstrated, utilizing metal deposition and patterning methodology based on combined focused ion and electron beam induced decomposition of a metal−organic precursor gas. Ohmic contacts were fabricated using electron beam deposition, followed by the faster process of ion beam deposition for interconnect formation. Two applications of this method are demonstrated: three-terminal transport measurements of Y-junction carbon nanotubes and fabrication of nanocircuits for determination of electromechanical degradation of silver nanowires.

Focused-ion-beam platinum nanopatterning for GaN nanowires: Ohmic contacts and patterned growth

“…In general, I-beam deposition conditions must be carefully chosen to avoid significant damage or complete destruction of the sample by massive Ga + ions. 5 We found no evidence for such damage, but minor sputtering around the contact area was observed (Figure 1b inset). This might in fact improve contact properties by removing surface oxide.…”

“…Attracted by its convenience and versatility, several groups reported the use of direct Pt deposition by focused ion beam (FIB) to make metal contacts on Bi and Ag NWs 4,5 and carbon nanotubes 5 . This is done by locally decomposing a fine jet of organometallic vapor with the highly focused and spatially controlled Ga + ion beam (I-beam).…”

“…This is done by locally decomposing a fine jet of organometallic vapor with the highly focused and spatially controlled Ga + ion beam (I-beam). 5 Since most FIB systems are also equipped with high resolution scanning electron microscopy (SEM), the combination provides unique capabilities of fast and precise metal contact patterning. Here we demonstrate direct FIB nanopatterning of low resistance ohmic Pt contacts on n-type GaN NWs grown by Ga 2 O 3 -NH 3 reaction without intentional doping.…”

Electrical properties of platinum interconnects deposited by electron beam induced deposition of the carbon-free precursor, Pt(PF3)4

“…Reports thus far have made extensive use of lithographic, resist-based methods such as optical or electron beam lithography followed by metal evaporation and lift-off to make electrical contacts to semiconducting nanowires [1][2][3] and nanotubes, 4 allowing single nanowire or nanotube devices such as field-effect-transistors, 5,6 nanoelectromechanical systems, [7][8][9][10] and chemical sensors 11 to be demonstrated. Although successful, the process of contact definition to nanowires by metal evaporation through a lithography mask tends to be very time-consuming, with many processing steps, and normally is not applicable to fragile or flexible substrates.…”

Three-way electrical gating characteristics of metallic Y-junction carbon nanotubes

“…It was verified that this procedure results in high-quality Ohmic contacts, with contact resistances of the order of 1 k⍀. 18 The experimental setup for the electrical characterization is implemented on a Wentworth probe station and is shown in Fig. 1.…”