Design and fabrication of organic semiconductor devices and integrated circuits for RFID applications

Organic semiconductors have attracted considerable attention because they offer the potential for low-cost and flexible solar cells, light-emitting devices, and integrated circuits for applications such as radio frequency identification (RFID) tags. One of the main challenges in organic RFID tags is fabricating the high frequency rectifiers, due to the low mobility observed in organic semiconductors. This dissertation describes the design, fabrication and simulation of high frequency organic diodes, rectifiers and multi-stage rectifiers, as well as an integration process to make fully integrated organic RFID circuitry on flexible plastic substrates.;While shadow mask processing was used in previous work reported in the literature, in this work a photolithographic process was developed for the fabrication of organic vertical diodes. Current-Voltage (I-V) and rectifier circuit measurements were performed to study the electrical characteristics of the organic diodes. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) were used to investigate the metal/organic semiconductor interface as well as determine possible degradation mechanisms.;The organic diodes were optimized by studying different organic semiconductors, different metal contacts and thickness of the organic semiconductor thin film, and doping of the organic semiconductors. It was found that the highest frequency response was achieved from diodes with a 50 nm thick copper phthalocyanine (CuPc) film as the semiconductor, and gold and aluminum as the ohmic and Schottky contacts, respectively. A current density of 29.3 A/cm2 was obtained at an applied voltage of 5 V. The rectifier circuit based on these devices generated an output voltage of approximately 2 V from an AC input signal with zero-to-peak amplitude of 5 V at a frequency of 13.56 MHz.;A five mask, low temperature (< 120°C) photolithographic process was developed to integrate the organic diodes with capacitors and pentacene thin-film transistors. Integrated rectifiers were fabricated on both Polyethylene Naphthalate (PEN) and silicon wafer substrates based on this integration process. These integrated rectifiers showed similar characteristics to the discrete devices. These organic semiconductor based rectifier circuits were simulated using Simulation Program with Integrated Circuit Emphasis (SPICE). The simulations agreed with the measured results. The generated device models were employed for the design and optimization of organic integrated circuits. Multi-stage integrated rectifiers were designed and fabricated in order to achieve higher output voltages.