Radio Frequency Coplanar ZnO Schottky Nanodiodes Processed from Solution on Plastic Substrates

Abstract

Keywords: Schottky diode, radio frequency diodes, RFID, nanogap electrode, 13.56 MHz Main TextRadio Frequency Identification (RFID) is a rapidly growing technology used for wireless communication and the identification of objects in close proximity through radio waves. [1] Although already a billion dollar industry [2] , RFID technology promises substantial further growth by adopting fully printable processing routes. However, there remain several bottlenecks to be overcome before this opportunity can be realised, particularly pertaining to the high frequency performance of printable electronics.RFID tags are generally composed of a coupling element, or antenna, a direct current (DC) rectifier and integrated circuitry (IC). The rectifying element is by far the most important component in terms of high-frequency (HF) operation, as the logic may take place at much J. Semple et al., Small (2016), DOI: 10.1002/smll.201503110 2 lower frequencies than the RF base carrier frequency. Different frequency bands exist for different applications, though the current target for printable RFID is the widely employed 13.56 MHz band. [1] Conventionally, complementary metal-oxide-semiconductor (CMOS) technology favours the use of diode-connected metal-oxide-semiconductor field-effect transistors (MOSFETs) for rectification within this element. However, Schottky diodes, with their inherently lower voltage operation, lower series resistance and exponential currentvoltage relationship offer a superior choice for rectifiers. [4] There has been extensive work carried out in recent years to develop high frequency organic Schottky diodes following the pioneering work of Steudel et al. who demonstrated pentacene-based Schottky diode rectifiers operating at 50 MHz. [5] More recently C60-basedSchottky diodes with a cut-off frequency (fCO) up to 0.7 GHz have also been reported. [6] Diodes based on metal oxide materials (particularly In-Ga-Zn-O) have recently emerged as a promising material, demonstrating device performance up to and above 1 GHz. [7][8][9] Despite such promising results, manufacturing of these conventional staggered diodes relies on vacuum processing, which renders them incompatible with cost-effective large-volume product integration. To address this important bottleneck, recent work has been devoted to solutionprocessable organic diodes with adequate performance. [10][11][12] Si nanoparticles have recently been demonstrated as a potential route to solution processed diodes with cut-off frequencies as high as 1.6 GHz.[13] However, demonstrating high yield manufacturing of solution-processed diodes with cut-off frequency 50 MHz still remains a significant challenge.The operational frequency of Schottky diodes is inversely proportional to the product of the series resistance (RS) and junction capacitance (Cj). A common approach to boosting the device cut-off frequency is by reducing RS through the use of a high charge carrier mobility J. Semple et al., Small (2016) However, there are inherent problems with implementing...

Analysis of Schottky Contact Formation in Coplanar Au/ZnO/Al Nanogap Radio Frequency Diodes Processed from Solution at Low Temperature

“…16 The reason for this is the existence of an extrinsic capacitance contribution due to 3D coupling of the electrodes, which has not been taken into consideration. De Vries et al 57 devised an approximation for the extrinsic capacitance per unit length of coplanar electrodes using conformal mapping as:…”

“…16 These coplanar diodes feature asymmetric Al/Au metal electrodes separated by ≤ 20 nm (nano-gap) 17 and a thin layer of ZnO (<20 nm) which is solution-deposited on top. 16 Due to the extreme dimensionality and the coplanar nature of the device architecture, the ZnO diodes are able to operate at high frequencies enabling their integration in RF rectifying circuits manufactured on arbitrary substrates including plastic. 16 Despite their excellent potential, however, little is known about the all-important Au/ZnO interface that gives rise to the highly current rectifying behavior observed.…”

“…16 Due to the extreme dimensionality and the coplanar nature of the device architecture, the ZnO diodes are able to operate at high frequencies enabling their integration in RF rectifying circuits manufactured on arbitrary substrates including plastic. 16 Despite their excellent potential, however, little is known about the all-important Au/ZnO interface that gives rise to the highly current rectifying behavior observed. Therefore, understanding the mechanism of electron injection at the Au/ZnO interface, would provide valuable knowledge that could be used to further advance this interesting device concept as well as help to identify associated technology bottlenecks, if any.…”

Giant nonlinear response at a plasmonic nanofocus drives efficient four-wave mixing

“…In the context of plasmonics, this brings two advantages: polymers are straightforward to integrate within metallic nanostructures by solution processing (21), and their low refractive index minimizes propagation loss.…”

Формирование кристаллических слоев Cu-=SUB=-2-=/SUB=-O и ZnO методом магнетронного распыления и их оптическая характеризация

“…В последнее время наблюдается заметный рост публи-каций, посвященных росту оксидов меди, цинка, галлия и других металлов [1][2][3][4][5][6][7][8][9][10]. Интерес к оксидам опре-деляется в первую очередь их уникальными полупро-водниковыми свойствами.…”