Doping profiles studied by scanning tunneling spectroscopy

Abstract
Tunneling spectra have been measured at various locations on uniformly doped, ion-implanted, and epitaxial silicon samples. We find that the I-V characteristics consistently vary with the variation of doping concentrations. Significant differences in the I-V curves are observed between n- and p-type samples. Combined with the high resolution of scanning tunneling microscopes (STM), this principle can be used to obtain two-dimensional doping profiles in submicron VLSI circuits.