The scanning tunneling microscope (STM), introduced in 1981 by IBM physicists Gerd Binnig and Heinrich Rohrer, is widely credited with shining a light on atomic-level mysteries, giving rise to the field of nanotechnology, and forever altering the trajectory of modern electronics. It has become an essential tool in disciplines as diverse as semiconductor manufacturing, molecular biology and materials science. In 1986, Binnig and Rohrer received the Nobel Prize in Physics for their groundbreaking invention.
The STM works differently from the common optical microscope, which amplifies visible light through a lens. Instead, the STM employs the tiny electron-emitting tip of a tungsten needle, just a single atom wide, which is slowly scanned just a few angstroms over the surface of a sample. A low electrical charge tunnels between the tip and the surface; the current varies in strength depending upon the shape of the surface.
These variations are measured and translated into a visual representation that resembles a three-dimensional topographic profile, enabling researchers to study the structure’s surface atom by atom. Binnig and Rohrer’s first STM experiment involved inspecting the surface structure of a gold crystal. The STM provided unsurpassed spatial resolution, accurately depicting a landscape 100 angstroms square. Binnig remembers the first time he saw the results, on the night of March 16, 1981. “I couldn’t stop looking at the images,” he recalled. “It was entering a new world.”
The Nobel Committee agreed. The STM, they said, opened up “entirely new fields ... for the study of the structure of matter.”
Working at the IBM Zurich Research Laboratory in the late 1970s, Binnig and Rohrer both had backgrounds in superconductivity. They were mutually fascinated by the study of atomic surfaces — and frustrated by the lack of exploratory tools. The conventional microscope is highly useful for observing very small objects, but its optical lenses are powerless on objects smaller than a wavelength of light. The electron microscope can capture images of extremely small objects by directing electron beams toward an object — but not at the level of individual atoms. So Binnig and Rohrer conceived of an instrument that would allow them to see and manipulate atoms at the nanoscale level.
They built on the work of Russell D. Young, a researcher at the National Bureau of Standards, who in the 1960s and early 1970s combined a tunneling current with a scanning device to obtain information about the nature of metal surfaces. During their 27 months of development, they fine-tuned the design to accurately produce measurements on a minuscule scale. These included reductions in vibrations and noise as well as more precise control of the scanning tip’s location, movement, sharpness and shape. In January 1979, Binnig and Rohrer submitted their first patent disclosure on the STM. Soon after, with the help of fellow researcher Christoph Gerber, they began design and construction.
Announced in 1981, the STM had an immediate impact on broad swaths of science and industry, but nowhere more so than in semiconductors, where granular knowledge of materials and atomic-level behavior have enabled massive advances in chip miniaturization. In September 1985, IBM introduced a handheld version of the STM, and subsequent refinements improved the precision of the mechanical design and resulted in increasingly clearer images.
The STM soon proved capable of more than merely depicting atomic-scale imagery. The tool enabled scientists to manipulate individual atoms. To demonstrate this capability, IBM scientists Donald Eigler and Erhard K. Schweizer in 1990 used the STM to arrange xenon atoms so they spelled out “I-B-M,” a bit of technical showmanship that helped boost the credibility of nanotechnology. The ability to “get these pesky little atoms to stand still,” as Eigler recalled, opened the door for dramatic progress in building ever more complex and densely packed computer chips.
Decades after its invention, the STM continues to deepen our understanding of surface physics and chemistry, providing the basis for continuing advancements in the fields of metallurgy, biology and the study of magnetism. In 2011, IBM opened a research facility in Rüschlikon, Switzerland, dedicated to advancing nanoscience: the Binnig and Rohrer Nanotechnology Center.
The co-creator of the scanning tunneling microscope opened the door to nanoscience and won a Nobel Prize
The co-inventor of the scanning tunneling microscope won the Nobel Prize in Physics
IBM pioneered exploration of the nanoscale, leading to breakthroughs from computing and biotech to AI and climate science