Peter Vicca

An integrated double half-wave organic Schottky diode rectifier on foil operating at 13.56 MHz

We demonstrate an integrated organic double half-wave rectifier for use in organic radio frequency identification (RFID) tags. This rectifier comprises two organic Schottky diodes, each followed by a capacitor, integrated on the same foil. This rectifier delivers approximately twice the dc voltage of single half-wave rectifiers. Its offset voltage is merely 2 V. It is able to generate voltages of 10–14 V, which are necessary for driving current organic RFID multibit code generators, from an ac-input voltage of only 8–10 V amplitude, which are generated at rf magnetic fields of 0.9–1.3 A/m. Such fields are below the minimum required rf magnetic field strength set by standards.

Low-voltage gallium–indium–zinc–oxide thin film transistors based logic circuits on thin plastic foil: Building blocks for radio frequency identification application

In this work a technology to fabricate low-voltage amorphous gallium-indium-zinc oxide thin film transistors (TFTs) based integrated circuits on 25 µm foils is presented. High performance TFTs were fabricated at low processing temperatures (<150 °C) with field effect mobility around 17 cm2 /V s. The technology is demonstrated with circuit building blocks relevant for radio frequency identification applications such as high-frequency functional code generators and efficient rectifiers. The integration level is about 300 transistors.

Organic complementary oscillators with stage-delays below 1 μs

Recently, complex circuits of organic thin-film transistors have been shown. The use of complementary logic can significantly ease the design of large integrated circuits. However, the performance of complementary logic in organic thin-film technology has not been able to equivale that of unipolar logic, due to the difficulty to densely integrate and simultaneously optimize p-type and n-type transistors on a single substrate. Here, we develop an optimized complementary process for C60 n-type and pentacene p-type transistors, both having bottom-gate bottom-contact geometry. Using this complementary technology, we show ring-oscillators with a stage-delay below 1 μs at a supply-voltage of 20 V.

An Inductively-Coupled 64b Organic RFID Tag Operating at 13.56MHz with a Data Rate of 787b/s

RFID systems operating at a base carrier frequency of 13.56 MHz can use low-cost inductive antennas on foil. In parallel to this coil, a capacitor on foil is used for matching the resonance frequency at 13.56 MHz. This LC-antenna detects the signal transmitted by the reader and energizes the organic rectifier with an AC-voltage at 13.56 MHz. From this voltage the rectifier generates the DC supply voltage for the 64 b organic transponder chip, which drives the modulation transistor between the on and off state with a 64b code sequence.

Ultra-High Frequency rectification using organic diodes

In the present work, we demonstrate a plastic diode that can operate in the ultra-high frequency (UHF) band and rectify an incoming AC voltage at those frequencies.

An organic integrated capacitive DC-DC up-converter

In this paper a fully integrated organic DC-DC up-converter is presented in a pentacene p-type only technology. This 3-stage Dickson converter reaches a voltage conversion factor of 3 for a purely capacitive load and 2.5 for a 10 µA load current. The maximal output voltage goes up to 75 V and the Dickson core efficiency is 48 %. The clock signal is generated on-chip with a 9-stage ring oscillator, built with zero-Vgs load inverters. A tunable input voltage provides a tuning range of 30 %. The presented converter is designed for the on-chip generation of voltages for biasing a capacitive load. This converter draws 560 µA from a 20 V supply voltage. The chip area measures 2.8×2.1 mm2. This converter fulfills a direct need for bias voltages beyond the supply voltage that is uncovered in recent work on organic circuits.

Organic RFID Tags

Organic RFID tags are increasingly gaining credibility as a possible low-cost barcode replacement for product identification. This will only happen if organic RFID tags can operate in the frequency range defined by well-accepted EPC standards. This chapter evaluates the performance of existing organic RFID demonstrators and confirms that, based on lab scale demonstration of organic RFID tags, performance comparable to the EPC standards can be obtained. Moreover, the integration of sensors with the tags will enable added functionality and applications beyond pure identification.

Adhesion Promoting Polymer Interlayers for Ag Layers Deposited in OLED Processing

One of the main drivers for organic electronic research are the backplanes for flexible active-matrix displays using organic light-emitting diodes (AM-OLEDs). In our work, we processed organic thin-film transistors (OTFTs) at low temperatures (<160°C) on poly(ethylene naphthalate) (PEN) foils. There are several challenges in the integration of OLEDs on top of OTFT backplanes on a foil. One of them is the interlayer between the OTFT backplane and the OLEDs. For this layer, low-temperature crosslinkable, chemically resistant polymers are required, which, on the one hand, provide proper electrical insulation to OTFT and OLED devices and, on the other hand, can be processed reliably and provide good adhesion to the OLED anode. From the point of reflectivity and, therefore, light emission efficiency, Ag would be a preferred option. The challenge from the processing point of view is the poor adhesion of evaporated or e-beam deposited Ag on most surfaces. Commonly used microelectronic approaches such as sputtered metal or Ar pre-sputtering cannot be applied because of resulting surface leakage paths on the organic dielectric caused by dangling bonds. To address this issue, we tested a variety of low-temperature crosslinkable polymers (e.g., SU-8, parylene) regarding adhesion, roughness and processability and we measured the adhesion of the Ag deposited at different thicknesses using the Scotch tape test (ASTM D 3359). The best adhesion properties were obtained with parylene N allowing Ag layers with thicknesses up to 200 nm and surface roughness around 7–8 nm.

High-speed growth of pentacene thin films by in-line organic vapor phase deposition

Taking another step towards industrial production of devices based on organic semi-conductors, this work presents an extension of the organic vapor phase deposition technique to in-line geometry. A study of the in-line tool operation is carried out. It leads to the definition of a specific in-line deposition rate that qualifies the coating speed. It also allows for an understanding of processing parameter variations that lead to high deposition speeds. As a consequence, pentacene films are grown at in-line deposition rates of up to 1055μm2/s. This corresponds to web speeds of 2.1 m/min, equivalent to an average deposition rate of 105 Å/s in a static system. These films present a high uniformity, with a thickness standard deviation below 1.2% over 4 inch diameter substrates. Moreover, with transistor mobilities of up to 1.5 cm2/Vs, these pentacene films are of excellent electrical quality. This quality is conserved up to the highest deposition rates. Finally, 5-stage ring oscillators on foil based on a pentacene thin film deposited by in-line OVPD achieve a frequency of 24 kHz at a supply voltage of 20 V.

Functional Pentacene Thin Films Grown by In-Line Organic Vapor Phase Deposition at Web Speeds above 2 m/min

We show in this paper that the organic vapor phase deposition technique can advantageously be extended to an in-line system, where a susceptor moves at a constant speed underneath an elongated showerhead. Highly uniform pentacene films are grown at web speeds of up to 2.1 m/min, equivalent to an average deposition rate of 105 angstrom/s in a static system. These pentacene films are of high electrical quality as proven by transistor mobilities of up to 1.5 cm(2) V-1 s(-1) and five-stage ring oscillators on foil that achieve a frequency of 24 kHz at a supply voltage of 20 V