Related Experiment Video
Updated: Aug 7, 2026
05:39
Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
Effect of molecular binding to a semiconductor on metal/molecule/semiconductor junction behavior
Hossam Haick1, Jamal Ghabboun, Olivia Niitsoo
1Department of Materials and Interfaces and Chemical Support Services, Weizmann Institute of Science, Rehovot 76100, Israel.
The Journal of Physical Chemistry. B
|July 21, 2006
Summary
Gold-based diodes show opposite barrier height changes with molecular dipoles due to varied gold-molecule interactions at the interface. This impacts semiconductor device performance.
Area of Science:
- Materials Science
- Surface Science
- Semiconductor Physics
Background:
- Molecular monolayers on semiconductor surfaces are crucial for tuning electronic properties.
- Understanding the metal-molecule interface is key to designing functional diodes.
Purpose of the Study:
- To investigate the influence of molecular dipole moments on the effective barrier height of gold-GaAs diodes.
- To elucidate the role of chemical bonding and interface interactions in determining diode behavior.
Main Methods:
- Fabrication of diodes using evaporated gold on molecular monolayers adsorbed on GaAs.
- Characterization using in situ ultraviolet photoelectron spectroscopy-X-ray photoelectron spectroscopy (UPS-XPS), ex situ XPS, time-of-flight secondary ion mass spectrometry (TOF-SIMS), Kelvin probe, scanning microscopy, and current-voltage measurements.
Main Results:
- A linear but opposite dependence of effective barrier height on molecular dipole moment was observed.
- Stronger gold-disulfide binding interactions compared to gold-dicarboxylate interactions were identified.
- Different interface morphologies resulting from varied binding interactions were suggested.
Conclusions:
- The observed opposite effects of molecular dipoles on barrier height are attributed to distinct chemical interactions between gold and the molecule's binding groups.
- The binding group's interaction strength influences gold deposition morphology and, consequently, the diode's electrical properties.
Related Concept Videos
01:24Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
01:27Biasing of Metal-Semiconductor Junctions
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
01:22Semiconductors
There is variation in the electrical conductivity of materials - metals, semiconductors, and insulators that are showcased with the help of the energy band diagrams.
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
01:12Fermi Level Dynamics
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
01:11P-N junction
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
01:20Types of Semiconductors
Intrinsic semiconductors are highly pure materials with no impurities. At absolute zero, these semiconductors behave as perfect insulators because all the valence electrons are bound, and the conduction band is empty, disallowing electrical conduction. The Fermi level is a concept used to describe the probability of occupancy of energy levels by electrons at thermal equilibrium. In intrinsic semiconductors, the Fermi level is positioned at the midpoint of the energy gap at absolute zero. When...