SAM-mediated interface engineering for enhanced Schottky diode characteristics

Metal/insulator/semiconductor (MIS) contacts play a crucial role in semiconductor device technology, significantly impacting their reliability, stability, and performance. This study delves into the fabrication and characterization of Schottky diodes utilizing self-assembly monolayers (SAMs) on titanium dioxide (TiO₂). The diodes were configured as Al/SAMs/TiO₂/p-Si and their electrical characteristics were conducted through both current–voltage (I−V) and capacitance–voltage (C−V) measurements. The ideality factor (n) decreased from 3.3 for TiO₂ to 1.95 for TiO₂/CT17 and 1.85 for TiO₂/CT19. Similarly, the reverse saturation current (I₀) decreased from 9.2 × 10^–9 A for TiO₂ to 4.6 × 10^–9 A for TiO₂/CT17 and further to 1.1 × 10^–9 A for TiO₂/CT19. Barrier height (∅_b) determined by various methods shows the highest values for TiO₂/CT19, indicating decreased leakage current. Additionally, rectification ratios significantly improved for SAM-modified diodes, reaching values of 6 × 10⁴ for TiO₂/CT19. The integration of SAM molecules significantly reduces interface defects and enhances the electrical properties of Schottky diodes, as evidenced by the distinct capacitance behavior observed across varying frequencies. The capacitance trends in SAM-modified diodes, including the emergence of negative capacitance at high frequencies, highlight the impact of SAM functional groups on interface state dynamics. Furthermore, series resistance (R_s) values showed a decreasing trend with SAM modification, implying enhanced charge transport. This study highlights the potential of SAMs in optimizing Schottky diodes, contributing to the development of the next-generation nanoelectronic devices.