Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy

Abstract

The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (∼1.5 nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.

Detection of silicide formation in nanoscale visualization of interface electrostatics

“…14 Schottky barrier mapping is performed by acquiring thousands of BEEM spectra on a grid of tip positions, which are then fit to the Bell and Kaiser (BK) model to extract the local threshold, from which a false-color image of the barrier height can be generated. 13,[15][16][17][18][19][20][21][22] Nanoscale localizations in the electrostatic barrier height are now detectable and when combined with modeling provide a new transformative means to visualize the interface electrostatics. 13 Improvements in correlating meV shifts in the local barrier height that occur due to incomplete silicide formation or inclusion of foreign species are needed and will extend the capabilities of the technique.…”

Relating spatially resolved maps of the Schottky barrier height to metal/semiconductor interface composition

“…Mapping of the SBH is achieved by fitting the spatially resolved transmission as a function of tip bias to extract the local SBH at individual tip locations and can achieve nanoscale resolution [15][16][17][18][19][20][21] [20]. However, no studies have measured the Schottky interface of mixed Au and Ag on the Si(001) substrate, which would be insightful for pinch-off effects due to the large differences in their barrier height's (∼ 0.2 eV) and their miscibility [25].…”

Dual parameter ballistic electron emission spectroscopy analysis of inhomogeneous interfaces

“…18 The dual parameter density plot for the Au/pentacene/n-Si interface ͑Fig. The fabrication process is similar to the Au/n-Si͑111͒ shown previously.…”