The scanning tunneling microscope - STM - was invented by Gerd Binnig and Heinrich Rohrer, who shared the Nobel Prize in physics in 1986 with Ernst Ruska, creator of the electron microscope.

The STM uses - as the previous writeup says - the quantum tunneling effect to make an image of the specimen. The STM probe is usually made out of tungsten, and is incredibly sharp; the tip is usually only made up of one or two metallic atoms. The specimen has to be metallic too for electric currents to run, and therefore it is common to cover it with a thin layer of gold.

The operation of the STM is controlled by piezoelectric elements that keep the tunneling current constant by holding the probe tip on a constant distance to the surface. The tunneling current is exponentially proportional to the distance between the needle and the metallic surface. As the probe sweeps over the surface of the sample, a topographical picture of it is created.