Bret Flanders

Dr. Bret N. Flanders


Oklahoma State University


Directed Electrochemical Nanowire Assembly

Tuesday, October 16, 2007

4:30 p.m.

Cardwell 102


Directed Electrochemical Nanowire Assembly (DENA) technique is a single-step approach to fabricating metallic nanowires and interconnecting them with external circuitry. We have previously shown that these are near single crystalline metallic nanowires and that they interconnect with on-chip electrodes with very small contact resistances, of the order of 10 W.[1, 2] Here we identify dendritic solidification as an important component of the DENA process, and exploit this mechanism to realize diameter-tunable nanowire growth. The experimental parameter that provides this control is the frequency w of the alternating voltage that induces the DENA process. Increasing w increases the metal cation concentration gradient at the wire-solution interface, thereby increasing the growth velocity of the wire. In turn, the anti-correlation between growth velocity and tip-radius, a fundamental characteristic of dendritic solidification, gives rise to a wire of reduced diameter. For indium wires, increasing w from 0.5 to 3.5 MHz increases the growth velocity of the wires from 11 to 78 mm/s and reduces their diameter from 770 to 114 nm. Gold wires exhibit diameter-tunability that ranges from ~1 mm down to 45 nm. Thus, it is possible to tune the wire diameter from the microscale down to the nanoscale. Recent results on the user-specified directional growth of these nanowires will be presented, as well. This combination of capabilities will enable the future interrogation of the intrinsic transport properties of nanomaterials.

[1]        Ozturk B, Mishima T, Grischkowsky D R and Flanders B N "Single step growth and low resistance interconnecting of gold nanowires," 2007 Nanotechnology 18, 175707.

[2]        Talukdar I, Ozturk B, Mishima T D and Flanders B N "Directed growth of single crystal indium wires," 2006 Appl. Phys. Lett. 88, 221907.