Molecularly Modified Schottky Diodes with Different Conjugation Degree of Organic Molecules

Date
2020-06-02
Authors
Tamara Samir Sliman Diek
تمارا سمير سليمان دعيق
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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.
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