Self-assembly monolayer impact on Schottky diode electrical properties

Abstract

This study examines the electrical and charge transport properties of p-Si/TiO₂/self-assembly monolayer (SAM)/Al type Schottky diodes. The diodes were fabricated by applying the SAM molecule 4′-[(3-methylphenyl)(phenyl)amino]biphenyl-4-carboxylic acid (CT21) onto titanium dioxide (TiO₂) synthesized via the sol-gel method. The key parameters, including the ideality factor (n), series resistance (R_s), and barrier height (∅_b), were used to assess the impact of CT21 on diode performance. Experimental results revealed that using CT21 at the TiO₂/Al interface significantly enhances diode performance. The n decreased from 3.8 in the control diode to 1.9 with CT21. R_s was substantially reduced, and the ∅_b increased. The rectification ratio improved from 1x10⁴ in the control diode to 1.1x10⁵ in the CT21-modified diode. These enhancements, due to the CT21 molecule's ability to reduce interface states (N_ss) and improve surface properties, underscore the potential of SAM coatings to open a new window in nanoelectronics with better performance and reliability.