Tracking Cation Exchange in Individual Nanowires via Transistor Characterization

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Cation exchange offers a versatile route for tailoring nanostructure composition and properties.
• Precise control over material properties at the single-particle level remains a significant challenge.

Purpose of the Study:

• To develop and demonstrate a method for monitoring and controlling material and electronic property changes in nanostructures during cation exchange at the single-particle level.
• To investigate the transformation from cadmium selenide (CdSe) to silver selenide (Ag2Se) in individual nanowires.

Main Methods:

• Fabrication of field-effect transistor devices using directly synthesized CdSe nanowires.
• Sequential cation exchange by submerging devices in silver nitrate solution.
• In-situ monitoring of electrical transport properties (conductivity and charge-carrier mobility) at various stages of the exchange reaction.

Main Results:

• Electrical conductivity was tuned over 8 orders of magnitude, and charge-carrier mobility over 7 orders of magnitude during the CdSe to Ag2Se exchange.
• Energy dispersive X-ray spectroscopy confirmed successful CdSe to Ag2Se cation exchange.
• X-ray fluorescence spectroscopy indicated cation exchange occurred even beneath device contacts.

Conclusions:

• The presented method enables non-destructive tuning of material composition and property characterization at the single-nanostructure level.
• This approach is applicable to diverse material systems for studying composition-dependent electrical properties or post-fabrication device optimization.