Undergraduate Student Work


Open Access Undergraduate Student Work

Type of Work

Poster Presentation


The metal/semiconductor interface is of vital importance to a number of electronic devices. The energy barrier that forms at this interface can dominate the overall electronic properties of a device. A poor interface can prevent a device from reaching its full potential. Thus, a better understanding of the mechanisms that determine this barrier could aid in the optimization of an interface for a particular application. For the current project, electrons were shot into gold films deposited on a molybdenum disulfide (γ€–π‘€π‘œπ‘†γ€—_2) semiconductor at different voltages using a scanning tunneling microscope in a ballistic electron configuration. The number of electrons entering the γ€–π‘€π‘œπ‘†γ€—_2 as a function of voltages can be used to determine the energy barrier, or threshold voltage, at this interface by fitting individual spectrum to the theory. For this project, spectra were taken in a grid fashion (10x10) to examine the energy barrier at different locations on the sample to investigate how impurities affect the quality of the interface. To do so each spectrum had to be fitted individually, a time consuming task. To make this process more efficient, a program was written in MATLAB to automate this process. The program was used to prepare the raw data to fit to theory. The fitted data was used to create an energy barrier map of the interface, displaying areas where it is easy or hard for electrons to traverse the interface. This current map lacks the resolution to identify impurities. However, in the future a 500x500 matrix should be sufficient.

Date of Work

Summer 2018


Department of Physics

First Advisor

Andrew Stollenwerk


Summer 2018 U. S. Army, REAP Internship, University of Northern Iowa, Department of Physics, Cedar Falls, Iowa


UNI ScholarWorks, University of Northern Iowa, Rod Library


Β©2018 Willie Brown and Andrew Stollenwerk



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