Article

Tuning tunneling current rectification with chemical modification of silicon(100) surfaces

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Abstract

Current–voltage characteristics of tunnel contacts to n+-Si(1 0 0) surfaces are modified through covalently bonded molecules. Scanning tunneling microscopy is used to characterize tunnel contacts to clean, hydrogen terminated and styrene terminated surfaces. The clean surface has pinned energy bands by silicon π∗ surface states resulting in an absence of rectification. Passivation with hydrogen removes band pinning and allows minority and majority carrier transport and a 1:10 forward/reverse current rectification ratio (RRF/R). Styrene also removes band pinning however, it introduces a surface dipole that limits the reverse bias to minority carrier transport and an opposite RRF/R of 10:1 is observed.

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... The 1250 C compares well with other literature spectroscopic observations of hydrogen terminated silicon. 14,16,35 However, it is clear that the sample heated to 1250 C reveals no observation of dopant current as measured for the sample heated to only 1050 C. The quality of the STM images (not shown) for both samples were comparable and show ideal 2 Â 1 reconstructed surfaces. Figure 2 shows the imaging of dangling bonds on the two hydrogen terminated surface. ...
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