Observation of <i>p</i> <i>n</i> junctions on implanted silicon using a scanning tunneling microscope

Abstract

Si pn junctions fabricated by photoresist masked As+ implantation were observed using current imaging tunneling spectroscopy (CITS) in a scanning tunneling microscope (STM). Using the CITS, a specific bias was chosen to define n-type or p-type areas according to whether or not current flowed. The pn junctions could be easily identified from the current image at this bias and in the STM topographic image. It also proved possible to find processing faults related to implantation. The STM images also identified the structure (corrugations) near the junctions, associated with volume expansion caused by implantation and annealing.