What is Scanning Tunneling Microscopy? Allows for the imaging of the surfaces of metals and semiconductors at the atomic level. Developed by Gerd Binnig and Heinrich Rohrer at the IBM Zurich Research Laboratory in The two shared half of the 1986 Nobel Prize in physics for developing STM. BinnigRohrer STM has fathered a host of new atomic probe techniques: Atomic Force Microscopy, Scanning Tunneling Spectroscopy, Magnetic Force Microscopy, Scanning Acoustic Microscopy, etc.
STM: scanning tunneling microscope nA R piezo- element e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- < 1nm tunneling of electrons through air between probe and surface only conducting material probe x-y stage
Basic Principles of STM Electrons tunnel between the tip and sample, a small current I is generated (10 pA to 1 nA). I proportional to e -2κd, I decreases by a factor of 10 when d is increased by 1 Å. d ~ 6 Å Bias voltage: mV – V range
Two Modes of Scanning Constant Height Mode Constant Current Mode Usually, constant current mode is superior.
Examples of STM images… Pt (100) with vaccancies Pt (100) with vaccancies Si (111) 7x7 reconstructio n Si (111) 7x7 reconstructio n Annealed decanethiol film on Au(111) Annealed decanethiol film on Au(111) Si (111) with terraces and vaccancies Si (111) with terraces and vaccancies