A very sensitive photodector based on molybdenum disulphide with potential for integrated optoelectronic circuits, light sensing, biomedical imaging, video recording or spectroscopy is now demonstrated.

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Ultrasensitive photodetectors based on monolayer MoS2.

Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

In this paper, recent progress of binary metal-oxide resistive switching random access memory (RRAM) is reviewed. The physical mechanism, material properties, and electrical characteristics of a variety of binary metal-oxide RRAM are discussed, with a focus on the use of RRAM for nonvolatile memory application. A review of recent development of large-scale RRAM arrays is given. Issues such as uniformity, endurance, retention, multibit operation, and scaling trends are discussed.

Metal–Oxide RRAM

Over the past 25 years, organic field-effect transistors (OFETs) have witnessed impressive improvements in materials performance by 3–4 orders of magnitude, and many of the key materials discoveries have been published in Advanced Materials. This includes some of the most recent demonstrations of organic field-effect transistors with performance that clearly exceeds that of benchmark amorphous silicon-based devices. In this article, state-of-the-art in OFETs are reviewed in light of requirements for demanding future applications, in particular active-matrix addressing for flexible organic light-emitting diode (OLED) displays. An overview is provided over both small molecule and conjugated polymer materials for which field-effect mobilities exceeding > 1 cm2 V–1 s–1 have been reported. Current understanding is also reviewed of their charge transport physics that allows reaching such unexpectedly high mobilities in these weakly van der Waals bonded and structurally comparatively disordered materials with a view towards understanding the potential for further improvement in performance in the future.

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25th anniversary article: organic field-effect transistors: the path beyond amorphous silicon.

This review covers important advances in recent years in the physics of thin-film ferroelectric oxides, the strongest emphasis being on those aspects particular to ferroelectrics in thin-film form. The authors introduce the current state of development in the application of ferroelectric thin films for electronic devices and discuss the physics relevant for the performance and failure of these devices. Following this the review covers the enormous progress that has been made in the first-principles computational approach to understanding ferroelectrics. The authors then discuss in detail the important role that strain plays in determining the properties of epitaxial thin ferroelectric films. Finally, this review ends with a look at the emerging possibilities for nanoscale ferroelectrics, with particular emphasis on ferroelectrics in nonconventional nanoscale geometries.

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Physics of thin-film ferroelectric oxides

We successfully fabricated the highly sensitive and reliable X-ray flat panel detector with HgI 2 photoconductor and Oxide drive TFT. The HgI 2 was fabricated by screen printing of paste and various properties were tested. The HgI 2 has 3 times higher sensitivity than a-Se at the applied bias below 150V. Also it shows better stability under high accumulation dose and humidity. As a drive TFT, HfInZnO oxide TFT was used and it has lower leakage current and higher mobility than a-Si TFT indicating the improvement of signal-to-noise. These are very promising results for applications in large area X-ray flat panel detector with higher X-ray sensitivity and lower dose requirement for Mammography imaging.

Highly sensitive and reliable X-ray detector with HgI 2 photoconductor and oxide drive TFT

Ferroelectric capacitors of Pt/PbZrTi1−xTi1−xO3/Pt system were integrated to examine the various capacitor structures. Three test structures of PZT capacitors were chosen for the fabrication and comparison. These were classified by how the capacitor area was defined and whether the sacrificial area of PZT film existed. Process integration includes back-end processing as well as ferroelectric processing. PZT and Pt thin films were prepared by metallo-organic decomposition (MOD) and DC magnetron sputtering, respectively. TiO2 was employed as a reaction barrier layer between PZT and SiO2 interlayer dielectric layer. Process flows for the fabrication of test capacitors have been developed for the device integration. Finally, the test structures of PZT capacitors were evaluated in terms of the electrical properties of the capacitors including hysteresis loop, fatigue, and leakage current as well as process integration.

Fabrication and comparison of ferroelectric capacitor structures for memory applications

There are difficulties in the nucleation of Al on SiO 2 and polymer surfaces at temperatures below 100°C using MPA as the Al precursor. In this study, Al/Co bilayer structures were deposited on SiO 2 or tris-(8-hydroxyquinoline) aluminum (Alq 3 ) surfaces at a low temperature of 70°C using a consecutive chemical vapor deposition (CVD) method. The use of Co 2 (CO) 8 as a precursor allowed the deposition of a continuous Co thin film on SiO 2 at 70°C, which provided effective nucleation sites for Al CVD at the same temperature. The predeposited Co underlayer was used to promote the nucleation of Al using MPA as the Al precursor. This resulted in the deposition of uniformly thick Al thin films with a smooth surface morphology (root-mean-square = 7.3 nm for 110 nm thick Al), a low resistivity of 4.2 μΩ cm, and negligible carbon contamination. Compared with the continuous films of Co on SiO 2 , there is isolated growth of Co on Alq 3 surfaces, which resulted in Al thin films with a rough surface (root-mean-square = 83.2 nm for 70-140 nm Al), a resistivity of 3.4-7.5 μΩ cm, and 3.0 atom % C contamination.

Consecutive CVD of Al/Co Bilayers on SiO 2 or Alq 3 Surfaces at Low Temperature of 70°C

The etching damage was studied on lead zirconate titanate (PZT) thin film capacitors with RuOx/Pt multi-layered electrodes. PZT films were deposited on RuOx/Pt/Ti/SiO2/Si substrates by spin coating with the sol-gel solution and etched by an inductively coupled plasma (ICP) etcher. Etching damage was systematically investigated by varying etching parameters such as coil RF power, DC bias to wafer susceptor, and chamber pressure. Quantitative analysis of etching damage was made in terms of the degree of the coercive field shift (Eshift ) in hysteresis loops. In this study, the optimization of etching process for PZT films was attempted to minimize the etching damage to the ferroelectric capacitors.

Etching effects to PZT capacitors with RuOx/Pt electrode by using inductively coupled plasma

Retention characteristics of a ferroelectric random access memory (FRAM) devices are strongly influenced by the integration processes and the ferroelectric material itself. In this study, we investigated the retention behavior of the PZT-based 4Mbit FRAM devices. Various heat treatment conditions were introduced to crystallize PZT films and the effect of La-doping was also observed. The nonvolatile charge of the PZT capacitor generally decreased as the increase of the baking time and finally the device failed to maintain the data. The decay rate of a sample, which was obtained through fitting the measured polarization values to the stretched exponential equation, was closely related to the crystallization process of PZT. It was also confirmed that the amount of the polarization decay varied due to the write/read voltages and baking temperature. Additionally, 1/T dependence of the logarithmic decay rate gave the activation energies for the polarization decay. The obtained activation energies were ...

Chang Jung Kim

Papers

Highly sensitive and reliable X-ray detector with HgI 2 photoconductor and oxide drive TFT

Fabrication and comparison of ferroelectric capacitor structures for memory applications

Consecutive CVD of Al/Co Bilayers on SiO 2 or Alq 3 Surfaces at Low Temperature of 70°C

Etching effects to PZT capacitors with RuOx/Pt electrode by using inductively coupled plasma

Retention behavior of ferroelectric memory devices depending on the capacitor processes