The development of the family of scanning probe microscopes starts with the original invention of the STM in 1981. Gerd Binnig and Heinrich Rohrer developed the first working STM while working at IBM Zurich Research Laboratories in Switzerland. This instrument would later win Binnig and Rohrer the Nobel prize in physics in 1986. The STM is based on several principles. One is the quantum mechanical effect of tunneling. It is this effect that allows us to “see” the surface. Another principle is the piezoelectric effect. It is this effect that allows us to precisely scan the tip with angstrom-level control. Lastly, a feedback loop is required, which monitors the tunneling current and coordinates the current and the positioning of the tip.The basic principle of scanning tunneling microscopy (STM) is based on the tunneling current between a metallic tip, which is sharpened to a single atom point and a conducting material.A small bias voltage (mV to 3 V) is applied between a atomically sharp tip and the sample. If the distance between the tip and the sample is large no current flows. However, when the tip is brought very close ( 10 Å) without physical contact, a current (pA to nA) flows across the gap between the tip and the sample.Such current is called tunneling current which is the result of the overlapping wave functions between the tip atom and surface atom, electrons can tunnel across the vacuum barrier separating the tip and sample in the presence of small bias voltage. The magnitude of tunneling current is extremely sensitivity to the gap distance between the tip and sample, the local density of electronic states of the sample and the local barrier height. The density of electronic states is the amount of electrons that exit at specific energy. As we measure the current with the tip moving across the surface, atomic information of the surface can be mapped out.