Ge/Si nanowire heterostructures as high-performance field-effect transistors.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Semiconducting carbon nanotubes and nanowires offer potential advantages over planar MOSFETs due to quantum confinement effects.
• While carbon nanotube FETs approach ballistic transport, challenges in uniform production hinder applications.
• Nanowires, including Ge/Si core/shell heterostructures, can be produced with reproducible properties suitable for large-scale integration.

Purpose of the Study:

• To investigate the performance of Ge/Si core/shell nanowire heterostructures configured as field-effect transistors (FETs).
• To compare the performance of these nanowire FETs (NWFETs) against state-of-the-art MOSFETs and carbon nanotube FETs.
• To evaluate the potential of NWFETs for high-performance electronic applications.

Main Methods:

• Fabrication of Ge/Si core/shell nanowire heterostructures into top-gate FETs utilizing high-kappa dielectrics.
• Characterization of electronic properties, including scaled transconductance and on-current.
• Analysis of intrinsic switching delay (tau = CV/I) for performance comparison.

Main Results:

• Ge/Si NWFETs achieved scaled transconductance of 3.3 mS/µm and on-current of 2.1 mA/µm, outperforming state-of-the-art MOSFETs by 3-4 times.
• These results represent the highest performance metrics reported for NWFETs to date.
• The intrinsic switching delay of Ge/Si NWFETs was found to be comparable to carbon nanotube FETs and superior to planar silicon MOSFETs, especially concerning length-dependent scaling.

Conclusions:

• Ge/Si core/shell NWFETs with high-kappa dielectrics exhibit exceptional performance, surpassing conventional MOSFETs.
• The reproducible fabrication and high performance of these NWFETs make them promising candidates for future integrated electronic systems.
• NWFETs offer a viable alternative to carbon nanotube FETs and demonstrate superior scaling potential compared to planar MOSFETs.