Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) are used to investigate a cross-sectional surface of Si(100) prepared by an ex situ cleave HF-dip technique. The agreement between the measured current–voltage spectra (I/Vs) and those calculated with an unpinned surface for both n- and p-type bulk surfaces is good, thus indicating that the prepared surface is unpinned and the model is valid. Both the experimental and calculated I/Vs show three components of current: tunneling out of valence-band states (VB), tunneling through dopant states (D), and tunneling into conduction-band states (CB). As demonstrated by experiment, in agreement with the model, the shape of the I/Vs allows the discrimination of n-type from p-type surfaces. Furthermore, the model indicates that by measuring the dopant state current D-component STM/STS is sensitive to the carrier density within the range of 1018–1021 cm−3. This suggests that this ex situ cleave sample preparation can be used to produce unpinned cross-sectional surfaces for ultra-shallow dopant profiles in Si(100). On such a surface STM/STS can be used to determine the carrier profile that results from the dopant profile.
No takes yet. Share an insight, caveat, or question.
Johnson et al. (1992) studied this question.