Approaching the Ballistic Transport Limit in Single Crystalline Au

Quantum conductance effects start to appear as the size of electronic devices decreases and they are used in the next generation memristors and quantum calculations. Understanding the relationship between line width and resistance is crucial for developing quantized electronic devices. This Letter reports the development of an electromechanical testing device based on microelectromechanical systems integrated within a transmission electron microscope for in situ investigations at atomic resolution. The resistance changes of single crystalline gold (Au) wires, spanning from hundreds of nanometers down to several atoms are investigated. A transition in resistance from quasiballistic to ballistic transport states is uncovered. The experimental data fitted by calculation show that the ballistic transport limit for single crystal Au at room temperature is about 2.5 nm, beyond which the transmission probability experienced a rapid drop.