DIRECT OBSERVATION OF POTENTIAL DISTRIBUTION ACROSS SI-SI P-N-JUNCTIONS USING OFF-AXIS ELECTRON HOLOGRAPHY

Off-axis electron holography was used to observe the potential distrib ution across a 2 x 10(18)/cm3 p- and n-doped Si/Si p-n junction. With digital image recording and processing, and a novel method for thickne ss determination, we have successfully extracted two-dimensional maps of the depletion region potential. For a defect-free region, we measur ed relatively abrupt changes in potential in the range 1.0-1.5 V acros s lateral distances of 20-30 nm. Although influenced by instrumental a nd sample limitations, these values are reasonably consistent with exp ected Si junction parameters and thus establish the promise of this te chnique for measuring potential distributions across device junctions and interfaces. (C) 1994 American Institute of Physics.