Using a new, high resolution, microscopic Scanning Kelvin Probe (SKP), work function topographies of metal, semiconductor and metal/semionductor surfaces have been studied in both Ultra-High-Vacuum (UHV) and air environments.
The work function is a very sensitive indicator of surface and Interface condition and has been previously utilized to examine preparation methods, surface roughness, adsorption processes, thin film monitoring and residual surface contamination.
Extension of the basic method, via Illumination of the semiconductor surface under the tip allows one to probe the local density of states (LDOS). Variations in LDOS can be used to monitor metal contamination, interface traps, bulk contamination, oxide imperfections, etc.
Work function topographies generated in this fashion have application in quality control at all stages of the manufacturing process. The Kelvin method of measuring work function is non-contact and non-destructive, utilizing neither high fields nor large currents. It can be applied to a variety of environments ranging from UHV to air and at a wide range of temperatures.