Atomic Scale Alignment of Copper-Germanide Contacts for Ge Nanowire Metal Oxide Field Effect Transistors

• Published in: Nano letters Vol. 9; no. 11; pp. 3739 - 3742
• Main Authors: Burchhart, T, Lugstein, A, Hyun, Y. J, Hochleitner, G, Bertagnolli, E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.2009
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Physics; Quantum wires; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Transistors; Temperature dependence; Scanning electron microscopy; Schottky barriers; Field effect transistors; Chemical reactions; Interfaces; Monocrystals; Germanium; Barrier height; Nanowires; Copper; IV characteristic; Current density; Nanostructured materials; Heterostructures; Germanides
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl9019243

In this letter, we report on the formation, of copper-germanide/germanium nanowire (NW) heterostructures with atomically sharp interfaces. The copper-germanide (Cu3Ge) formation process is enabled by a chemical reaction between metallic Cu pads and vapor−liquid−solid (VLS) grown Ge-NWs. The atomic scale aligned formation of the Cu3Ge segments is controlled by in situ SEM monitoring at 310 °C thereby enabling length control of the intrinsic Ge-NW down to a few nanometers. The single crystal Cu3Ge/Ge/Cu3Ge heterostructures were used to fabricate p-type Ge-NW field effect transistors with Schottky Cu3Ge source/drain contacts. Temperature dependent I /V measurements revealed the metallic properties of the Cu3Ge contacts with a maximum current density of 5 × 107 A/cm2. According to the thermoionic emission theory, we determined an effective Schottky barrier height of 218 meV.