2-D materials, such as molybdenum-disulfide (MoS₂), are attracting much attention for future electronic and photonic applications ranging from high-performance computing to flexible and pervasive sensors and optoelectronics. But in order for their promise to be realized, scientists need to understand how the performance of devices made with 2-D materials is affected by different kinds of metal electrical contacts.

Researchers in Physical Measurement Laboratory (PML)’s Semiconductor & Dimensional Metrology Div., in collaboration with researchers from George Mason Univ., compared silver and titanium contacts on MoS₂ transistors to determine the influence of the metal–MoS₂ interface. A sophisticated suite of measurements (Raman spectroscopy, scanning electron microscopy and atomic force microscopy) was used to characterize the surface morphology and the interface between MoS₂ and the metals, the properties of which affect the device behavior. It was found that silver provides a much better electrical contact to MoS₂ than the widely used titanium, with the silver-contact devices having 60 times higher current when the device is in the “on” state. These results are another step towards the advanced manufacture of high-value products based on 2-D materials.

Source: NIST