Characterization of gold contacts in GaAs-based molecular devices: Relating structure to electrical properties

Patrick D. Carpenter, School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University
Saurabh Lodha, School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University
David B. Janes, Purdue University
Amy V. Walker, Washington University

Abstract

Au/octadecanethiol/GaAs devices were prepared using different metallization conditions: direct deposition at 77 K and 300 K samples, and indirect deposition (Ar backfilling). Time-of-flight secondary ion mass spectrometry data indicate that similar to 4x and similar to 2x more gold penetrates through the SAM after direct deposition at 300 K and 77 K, respectively, than under Ar backfill conditions. However, these devices have significantly different conductances: Ar-backfill and 77 K samples have similar to 200x and similar to 70x, respectively, larger conductances than 300 K devices. An electrostatic model has been developed to explain the very large conductance changes due to small differences in device structure.

Discipline(s)

Nanoscience and Nanotechnology