Scanning Tunneling Microscope: 3D Imaging on the Atomic Level
Faculty Mentor Information
Elton Graugnard Steve Hues
Abstract
A Scanning Tunneling Microscope (STM) is a very useful tool in Physics and Material Science with its ability to image surfaces with atomic-scale resolution making it a critical instrument for the surface analysis of conductive materials. In operation, the STM utilizes a fluctuation in tunneling current between the tip of a needle and surface atoms to track the contours of the electron density of surface atoms. The needle and surface are so close that electrons can quantum mechanically tunnel (hence the name tunneling current) across the classically forbidden vacuum barrier between the two generating a tiny, but measurable, current. As the probe tip moves along a surface, the sample’s change in topography (or composition) will affect the tunneling current. If the tip is raised or lowered to maintain a constant tunneling current, then the change in the tip position may be processed into a contour map of the surface. The ability to visualize surface atoms provides valuable information for materials science, semiconductor physics, and microelectronics and has been used to determine the atomic structure of semiconductor surfaces, visualize atomic and molecular orbital structures, and even manipulate single atoms.
Scanning Tunneling Microscope: 3D Imaging on the Atomic Level
A Scanning Tunneling Microscope (STM) is a very useful tool in Physics and Material Science with its ability to image surfaces with atomic-scale resolution making it a critical instrument for the surface analysis of conductive materials. In operation, the STM utilizes a fluctuation in tunneling current between the tip of a needle and surface atoms to track the contours of the electron density of surface atoms. The needle and surface are so close that electrons can quantum mechanically tunnel (hence the name tunneling current) across the classically forbidden vacuum barrier between the two generating a tiny, but measurable, current. As the probe tip moves along a surface, the sample’s change in topography (or composition) will affect the tunneling current. If the tip is raised or lowered to maintain a constant tunneling current, then the change in the tip position may be processed into a contour map of the surface. The ability to visualize surface atoms provides valuable information for materials science, semiconductor physics, and microelectronics and has been used to determine the atomic structure of semiconductor surfaces, visualize atomic and molecular orbital structures, and even manipulate single atoms.