Molecularly Modified Schottky Diodes with Different Conjugation Degree of Organic Molecules
Date
2020-06-02
Authors
Tamara Samir Sliman Diek
تمارا سمير سليمان دعيق
Journal Title
Journal ISSN
Volume Title
Publisher
Al-Quds University
Abstract
Functional and atomically precise molecules may be the primary
building block of future electronic devises. However, integrating them into circuits
requires developing new ways to control the interference between molecules and
electrodes. In my project, I will conduct surface and electrical characterization to
show that systematic Schottky barrier height modulation can be achieved using
dipolar molecular layers with different conjugation degrees in a
metal/molecule/semiconductor device. Using Ag and Au as metal, Si and GaAs as
semiconductors, PEDOT and cinnamic acid as conjugated molecules, and PVA as
non-conjugated molecule.
The effect of molecular modification at the interface of a
metal/semiconductor device will be discussed through parameters analysis such as
barrier height and ideality factor. Molecules will be deposited on the surface of a
semiconductor using spin coating, followed by metal evaporation to form the
Schottky diode. Electrical characterization will be mainly carried out through currentvoltage
measurements. Furthermore, molecularly modified surface of semiconductor
will be characterized to study the dependence of the conductivity behavior of the
metal/molecule/semiconductor device on the topography of the deposited molecule on
the semiconductor.
The effect of molecules on the conductivity have been studied using
the current-voltage measurements and the Schottky barrier height. For Si-Ag, the
conjugated and non-conjugated molecules decreased the conductivity. For Si-Au,
conjugated molecules increased the conductivity but the non-conjugated molecule
decreased the conductivity. For GaAs-Ag, both conjugated and non-conjugated
molecules increased the conductivity. For GaAs-Au, the conjugated molecule
decreased the conductivity but the non-conjugated molecule increased the
conductivity.
Moreover, the effect of temperature on the conductivity have been
studied using the current-voltage measurements. For Si-Ag, increasing the
temperature increased the conductivity. For Si-cin-Ag, increasing the temperature
increased the conductivity at first then it started to decrease. For the Si-PEDOT-Au,
increasing the temperature decreased the conductivity. For the Si-PVA-Ag, increasing
the temperature increased the conductivity at first then it started to decrease. For
GaAs-Ag, increased the temperature decreased the conductivity and the voltage
became in the reverse bias. For the GaAs-Au, increasing the temperature increased the
conductivity at first then it started to decrease and the voltage became in the reverse
bias. For the GaAs-cin-Ag, increasing the temperature increased the conductivity at
first then it started to decrease and the voltage became in the reverse bias. For the
GaAs-PVA-Ag, increasing the temperature increased the conductivity at first, then it
started to decrease and the voltage became in the reverse bias. For the GaAs-Au,
increasing the temperature increased the conductivity at first then it started to
decrease.
In addition, the effect of increasing the thickness of cinnamic acid
molecule on Si-cinnamic acid-Ag have been studied, and concluded that increasing
the thickness in this case increased the conductivity.