Dopant and Carrier Concentration Profiling with Atomic Resolution by Scanning Tunneling Microscopy

Abstract

We show that the scanning tunneling microscopy (STM) has the ability to detect the surface potential and the individual dopant atoms with extremely high spatial resolution on flat and electrically inert Si surfaces. The actual measurements are demonstrated for both the ultra-thin oxidized surface and the NH4F-treated Si (111) surface. The latter treatment yields atomically flat hydrogenated surfaces, on which atomic resolution is available. This surface enabled us to analyze correlation between the potential variation and the statistical fluctuation of dopant atom distribution for a p-n junction region. Another example is quantitative potential profiling based on scanning resonance tunneling spectroscopy of molecular levels of C60 deposited on oxidized Si surfaces. Mechanisms of these measurements are discussed.