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Integrating two-dimensional (2D) materials into semiconductor manufacturing lines is essential to exploit their material properties in a wide range of application areas. However, current approaches are not compatible with high-volume manufacturing on wafer level. Here, we report a generic methodology for large-area integration of 2D materials by adhesive wafer bonding. Our approach avoids manual handling and uses equipment, processes, and materials that are readily available in large-scale semiconductor manufacturing lines. We demonstrate the transfer of CVD graphene from copper foils (100-mm diameter) and molybdenum disulfide (MoS2) from SiO2/Si chips (centimeter-sized) to silicon wafers (100-mm diameter). Furthermore, we stack graphene with CVD hexagonal boron nitride and MoS2 layers to heterostructures, and fabricate encapsulated field-effect graphene devices, with high carrier mobilities of up to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$4520\;{\mathrm{cm}}^2{\mathrm{V}}^{ - 1}{\mathrm{s}}^{ - 1}$$\end{document}4520cm2V−1s−1. Thus, our approach is suited for backend of the line integration of 2D materials on top of integrated circuits, with potential to accelerate progress in electronics, photonics, and sensing., The existing integration approaches for 2D materials often degrade material properties and are not compatible with industrial processing. Here, the authors devise an adhesive wafer bonding strategy to transfer and stack monolayers, suitable for back end of the line integration of 2D materials.

Ag/ZnO/cellulose nanocomposites were synthesised through in-situ solution casting method, which offers a good adhesion and dispersity of nanostructured materials. SEM analysis revealed formation of nanodiscs-like structures for ZnO while nanospheres and hierarchical nanosheets were observed for Ag and cellulose, respectively. XRD analysis pointed to the monoclinic type-1 phase of cellulose. Peaks corresponding to typical hexagonal wurtzite structure of ZnO and face-centredcubic Ag structure were also identified. Photodecomposition of aqueous methylene blue (MB) under direct sunlight irradiation was monitored to study the photocatalytic activity of the nanocomposite. About 92% of MB dye was photodegraded in the presence of Ag/ZnO/cellulose nanocomposite. The influence of Ag+ ions on the photocatalytic efficiency of ZnO is discussed. The antibacterial efficiency of the synthesised samples was investigated against two Gram positive pathogenic bacteria species: Staphylococcus aureus and a spore forming Bacillus subtilis as well as a Gram-negative Escherichia coli. The prepared nanocomposite exhibited strong activity against the growth of all the bacterial species though in different quantified measures.

Guanidinoacetic acid (GAA) is immediate substrate for biosynthesis of creatine (CREA). The phosphorylated form of CREA serves as a rapidly mobilisable reserve of high-energy phosphates in skeletal ...

In this study, the contact resistance of various metals to chemical vapour deposited (CVD) monolayer graphene is investigated. Transfer length method (TLM) structures with varying widths and separation between contacts have been fabricated and electrically characterized in ambient air and vacuum condition. Electrical contacts are made with five metals: gold, nickel, nickel/gold, palladium and platinum/gold. The lowest value of 92 {\Omega}{\mu}m is observed for the contact resistance between graphene and gold, extracted from back-gated devices at an applied back-gate bias of -40 V. Measurements carried out under vacuum show larger contact resistance values when compared with measurements carried out in ambient conditions. Post processing annealing at 450{\deg}C for 1 hour in argon-95% / hydrogen-5% atmosphere results in lowering the contact resistance value which is attributed to the enhancement of the adhesion between metal and graphene. The results presented in this work provide an overview for potential contact engineering for high performance graphene-based electronic devices.

A reliable method is proposed for measuring specific contact resistivity (pC) for graphenemetal contacts, which is based on a contact end resistance measurement. We investigate the proposed method with simulations and confirm that the sheet resistance under the metal contact (RSK) plays an important role, as it influences the potential barrier at the graphene-metal junction. Two different complementary metal-oxide-semiconductor-compatible aluminum-based contacts are investigated to demonstrate the importance of the sheet resistance under the metal contact: the difference in RSK arises from the formation of insulating aluminum oxide (Al2O3) and aluminum carbide (Al4C3) interfacial layers, which depends on the graphene pretreatment and process conditions. Auger electron spectroscopy and X-ray photoelectron spectroscopy support electrical data. The method allows direct measurements of contact parameters with one contact pair and enables small test structures. It is further more reliable than the conventional transfer length method when the sheet resistance of the material under the contact is large. The proposed method is thus ideal for geometrically small contacts where it minimizes measurement errors and it can be applied in particular to study emerging devices and materials.

Molybdenum disulfide (MoS 2 ) is a widely studied two-dimensional (2D) semiconductor with high potential as channel material in field effect transistors (FET) [1] . A major challenge for MoS 2 -based FETs is low hysteresis operation [2] . Al 2 O 3 is a common encapsulation layer or gate dielectric, even though it causes an n-doping effect on MoS 2 -FETs after their encapsulation [3] , [4] . Here, we present a method for scalable MoS 2 FET gate dielectric deposition and encapsulation using a stack of monolayer hexagonal boron nitride (h-BN) and Al 2 O 3 . This heterostructure prevents the n-doping effect of Al 2 O 3 and leads to reduced hysteresis even under ambient conditions.

The integration of 2D materials for photonic applications is not compatible with high-volume manufacturing. We report a generic methodology that uses only readily available semiconductor equipment and experimentally demonstrate the stacking of graphene and molybdenum disulfide (MoS2). Part of proceedings: ISBN 978-1-943580-91-0, QC 20230117

Integrated logic circuits require transistors that have a sufficiently high mobility, but also a high current on/off ratio. In this respect, two-dimensional (2D) molybdenum disulfide (MoS 2 ) has been demonstrated as a suitable channel material for n-type field-effect transistors (FETs) with high performance. Single-layer graphene (SLG) has been shown to reduce contact resistance in such MoS 2 devices [2] , [3] . Here, we experimentally demonstrate a scalable method for low resistivity contacts to MoS 2 using only chemical vapor deposited (CVD)-grown SLG, corroborated through simulations that explore the scalability potential of contact resistance optimization based on this approach.

Knowledge about the nutritional value of methionine sources is highly important for their appropriate application in terms of animal and economic performance. Therefore, a broiler feeding trial was conducted to determine the relative bioavailability value (RBV) of DL-2-hydroxy-4-methylthio butanoic acid (HMTBA) compared to DL-methionine (DLM). DLM diluted to 65% purity (DLM65) served as the internal standard, with a known RBV of 65%. A total of 1920 d-old male broilers were used in the three-phase feeding trial comprising 16 treatments including a basal, Met+Cys-deficient diet and 5 graded DLM, HMTBA, or DLM65 levels. Growth performance and carcass quality data were subjected to multi-exponential regression analysis. Increasing levels of any Met source significantly improved all performance parameters compared to the negative control (p &lt, 0.05). Across all performance parameters, the RBV of HMTBA was 63% and that of DLM65 was 58%. All RBV estimates of HMTBA and DLM65 were significantly lower than 88% (p &lt, 0.05). Cumulative efficiency of DLM for Met+Cys deposition in body protein was higher than that of HMBTA at any dose, confirming the determined RBV. Using DLM65 as an internal marker allowed for validation of the methodology.

Graphene-based photodetectors have shown responsivities up to 10$^8$A/W and photoconductive gains up to 10$^{8}$ electrons per photon. These photodetectors rely on a highly absorbing layer in close proximity of graphene, which induces a shift of the graphene chemical potential upon absorption, hence modifying its channel resistance. However, due to the semi-metallic nature of graphene, the readout requires dark currents of hundreds of $\mu$A up to mA, leading to high power consumption needed for the device operation. Here we propose a novel approach for highly responsive graphene-based photodetectors with orders of magnitude lower dark current levels. A shift of the graphene chemical potential caused by light absorption in a layer of colloidal quantum dots, induces a variation of the current flowing across a metal-insulator-graphene diode structure. Owing to the low density of states of graphene near the neutrality point, the light-induced shift in chemical potential can be relatively large, dramatically changing the amount of current flowing across the insulating barrier, and giving rise to a novel type of gain mechanism. This readout requires dark currents of hundreds of nA up to few $\mu$A, orders of magnitude lower than other graphene-based photodetectors, while keeping responsivities of $\sim$70A/W in the infrared, almost two orders of magnitude higher compared to established germanium on silicon and indium gallium arsenide infrared photodetectors. This makes the device appealing for applications where high responsivity and low power consumption are required., Comment: 14 pages, 7 figures

Atrial tachypacing is an accepted model for atrial fibrillation (AF) in large animals and in cellular models. Human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CM) provide a novel human source to model cardiovascular diseases. Here, we investigated whether optogenetic tachypacing of atrial-like hiPSC-CMs grown into engineered heart tissue (aEHT) can induce AF-remodeling. After differentiation of atrial-like cardiomyocytes from hiPSCs using retinoic acid, aEHTs were generated from ∼1 million atrial-like hiPSC-CMs per aEHT. AEHTs were transduced with lentivirus expressing channelrhodopsin-2 to enable optogenetic stimulation by blue light pulses. AEHTs underwent optical tachypacing at 5 Hz for 15 seconds twice a minute over 3 weeks and compared with transduced spontaneously beating isogenic aEHTs (1.95 ± 0.07 Hz). Force and action potential duration did not differ between spontaneously beating and tachypaced aEHTs. Action potentials in tachypaced aEHTs showed higher upstroke velocity (138 ± 15 vs. 87 ± 11 V/s, n = 15-13/3; P = 0.018), possibly corresponding to a tendency for more negative diastolic potentials (73.0 ± 1.8 vs. 68.0 ± 1.9 mV; P = 0.07). Tachypaced aEHTs exhibited a more irregular spontaneous beating pattern (beat-to-beat scatter: 0.07 ± 0.01 vs. 0.03 ± 0.004 seconds, n = 15-13/3; P = 0.008). Targeted expression analysis showed higher RNA levels of KCNJ12 [Kir2.2, inward rectifier (IK1); 69 ± 7 vs. 44 ± 4, P = 0.014] and NPPB (NT-proBNP; 39,690 ± 4834 vs. 23,671 ± 3691; P = 0.024). Intermittent tachypacing in aEHTs induces some electrical alterations found in AF and induces an arrhythmic spontaneous beating pattern, but does not affect resting force. Further studies using longer, continuous, or more aggressive stimulation may clarify the contribution of different rate patterns on the changes in aEHT mimicking the remodeling process from paroxysmal to persistent atrial fibrillation.

Platinum diselenide (PtSe 2 ) is a promising two-dimensional (2D) material of the noble-metal dichalcogenides (NMDCs), a subgroup of the transition-metal dichalcogenides (TMDCs). It has been shown to exhibit a high negative piezoresistive gauge factor (GF) [1] and a charge carrier mobility of up to 210 cm 2 /Vs while being air-stable for many months [2] . It can be grown at CMOS-compatible temperatures by thermally assisted conversion (TAC) [3] . PtSe 2 can be tuned from a semiconductor to a semimetal by varying the number of layers [4] – [7] . Experimental data of electronic devices based on PtSe 2 show large variations in the electronic properties that cannot be explained by the material thickness alone. Here, we show that the nanocrystalline structure of TAC-grown PtSe 2 films greatly influences the electronic properties of PtSe 2 -based devices.

Simple Summary There is a distinct possibility that synthetic and crystalline, or non-bound, amino acids will partially replace soybean meal in diets for broiler chickens and reduce the dependency of the chicken-meat industry on soybean meal as its principal source of protein. The genesis of this partial replacement will be the successful development of reduced-crude protein diets. A reduced-crude protein diet contains less soybean meal, and therefore less crude protein, but an increased array of essential and even non-essential non-bound amino acids so that requirements are met. There are, however, several challenges to be overcome if reduced-crude protein diets are to be successfully developed and adopted. Abstract This review explores the premise that non-bound (synthetic and crystalline) amino acids are alternatives to soybean meal, the dominant source of protein, in diets for broiler chickens. Non-bound essential and non-essential amino acids can partially replace soybean meal so that requirements are still met but dietary crude protein levels are reduced. This review considers the production of non-bound amino acids, soybeans, and soybean meal and discusses the concept of reduced-crude protein diets. There is a focus on specific amino acids, including glycine, serine, threonine, and branched-chain amino acids, because they may be pivotal to the successful development of reduced-crude protein diets. Presently, moderate dietary crude protein reductions of approximately 30 g/kg are feasible, but more radical reductions compromise broiler performance. In theory, an ‘ideal’ amino acid profile would prevent this, but this is not necessarily the case in practice. The dependence of the chicken-meat industry on soybean meal will be halved if crude protein reductions in the order of 50 g/kg are attained without compromising the growth performance of broiler chickens. In this event, synthetic and crystalline, or non-bound, amino acids will become viable alternatives to soybean meal in chicken-meat production.

Unparalleled strength, chemical stability, ultimate surface-to-volume ratio and excellent electronic properties of graphene make it an ideal candidate as a material for membranes in micro- and nanoelectromechanical systems (MEMS and NEMS). However, the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges, including collapse and rupture of the graphene. We have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on membranes with high yields. We have demonstrated the manufacture of square graphene membranes with side lengths from 7 micro meter to 110 micro meter and suspended proof masses consisting of solid silicon cubes that are from 5 micro meter multiply 5 micro meter multiply 16.4 micro meter to 100 micro meter multiply 100 micro meter multiply 16.4 micro meter in size. Our approach is compatible with wafer-scale MEMS and semiconductor manufacturing technologies, and the manufacturing yields of the graphene membranes with suspended proof masses were greater than 90%, with more than 70% of the graphene membranes having more than 90% graphene area without visible defects. The graphene membranes with suspended proof masses were extremely robust and were able to withstand indentation forces from an atomic force microscope (AFM) tip of up to ~7000 nN. The measured resonance frequencies of the realized structures ranged from tens to hundreds of kHz, with quality factors ranging from 63 to 148. The proposed approach for the reliable and large-scale manufacture of graphene membranes with suspended proof masses will enable the development and study of innovative NEMS devices with new functionalities and improved performances., 39 pages, 15 figures

Applied Sciences 10(6), 2183 (2020). doi:10.3390/app10062183, Published by MDPI, Basel

Non-volatile resistive switching is demonstrated in memristors with nanocrystalline molybdenum disulfide (MoS2) as the active material. The vertical heterostructures consist of silicon (Si), vertically aligned MoS2, and chrome/gold metal electrodes. Electrical characterizations reveal a bipolar and forming-free switching process with stable retention for at least 2500 s. Controlled experiments carried out in ambient and vacuum conditions suggest that the observed resistive switching is based on hydroxyl ions (OH−). These originate from catalytic splitting of adsorbed water molecules by MoS2. Experimental results in combination with analytical simulations further suggest that electric field driven movement of the mobile OH− ions along the vertical MoS2 layers influences the energy barrier at the Si/MoS2 interface. The scalable and semiconductor production compatible device fabrication process used in this work offers the opportunity to integrate such memristors into existing Si technology for future neuromorphic applications. The observed ion-based plasticity may be exploited in ionic-electronic devices based on transition metal dichalcogenides and other 2D materials for memristive applications.

We report the integration of graphene/hexagonal boron nitride (hBN) heterostructure devices on large-areas by adhesive wafer bonding, a method suitable for industrial mass-production. In this new approach, we stack graphene and hBN by two consecutive bond transfers whereby the graphene and its interface to hBN is not in contact with potentially contaminating polymers or adhesives at any time. To show the feasibility of our approach for back end of the line (BEOL) integration of two-dimensional (2D) material heterostructures on standard silicon substrates, we fabricated graphene/hBN devices with electrical bottom contacts using only established semiconductor manufacturing tools, processes and materials. QC 20200611

It was hypothesized that dietary guanidinoacetic acid (GAA), the precursor of creatine (Cr), would be beneficial to heat-stressed finisher broilers owing to improved cellular energy status and arginine sparing effects. A total of 720 one-day-old male Ross 308 broilers were allocated to 3 treatments, 0 (control), 0.6, or 1.2 g/kg of GAA added to complete corn–soybean meal diets, and were fed for 39 D, with 12 replicates (20 birds each) per treatment. A chronic cyclic heat stress model (at a temperature of 34°C and 50 to 60% relative humidity for 7 h daily) was applied in the finisher phase (day 25–39). Samples were taken on day 26 and 39 to determine thrombocyte, white blood cell, corticosterone, protein and amino acid levels in blood and Cr, phosphocreatine (PCr), and adenosine triphosphate levels in the breast muscle. Meat quality was assessed on day 40 after overnight fasting. Guanidinoacetic acid at a dose of 1.2 g/kg decreased feed-to-gain ratio compared with the control in the grower phase (1.32 vs. 1.35, respectively; P

Advanced optical materials 2000169 (2020). doi:10.1002/adom.202000169, Published by Wiley-VCH, Weinheim

Controlling the doping level in graphene during integration into silicon CMOS compatible devices is an open challenge. In general, the doping level in graphene is influenced via substrate interacti...

Heterostructures comprising silicon, molybdenum disulfide (MoS2), and graphene are investigated with respect to the vertical current conduction mechanism. The measured current-voltage (I-V) characteristics exhibit temperature-dependent asymmetric current, indicating thermally activated charge carrier transport. The data are compared and fitted to a current transport model that confirms thermionic emission as the responsible transport mechanism across devices. Theoretical calculations in combination with the experimental data suggest that the heterojunction barrier from Si to MoS2 is linearly temperature-dependent for T = 200-300 K with a positive temperature coefficient. The temperature dependence may be attributed to a change in band gap difference between Si and MoS2, strain at the Si/MoS2 interface, or different electron effective masses in Si and MoS2, leading to a possible entropy change stemming from variation in density of states as electrons move from Si to MoS2. The low barrier formed between Si and MoS2 and the resultant thermionic emission demonstrated here make the present devices potential candidates as the emitter diode of graphene base hot electron transistors for future high-speed electronics. Copyright �� 2020 American Chemical Society.

A novel layer-by-layer three-dimensional (3D) architecture allowing one to expand device fabrication in the vertical direction and integrating functional nanomaterials is presented by emulating civil engineering. The architecture uses SU-8 pillars as structural columns, which support multiple horizontal suspended thin films. The films then serve as platforms for the integration of nanomaterials and nanodevices. Multiple graphene layers suspended across SU-8 pillars with precise control on their vertical spacing are demonstrated. In addition to graphene, silicon nitride films that offer high strength yield and thickness control are also presented. Metallic microstructures, plasmonic nanostructures, semiconducting quantum dots, and monolayer graphene on the suspended films are achieved to prove the capability of integrating functional nanomaterials. This work provides the potential to integrate highly compact micro/nanoscale devices at different vertical levels with high surface density, which allows for more capabilities and functionalities in a single device.

This trial was conducted to compare Novel Met-Met product (AQUAVI® Met-Met) and dl -methionine ( dl -Met) regarding their availability to juvenile white shrimp. Eleven experimental diets were formulated (Basal, dl -Met 0.06, dl -Met 0.12, dl -Met 0.18, dl -Met 0.24, dl -Met 0.3, AQUAVI 0.06, AQUAVI 0.12, AQUAVI 0.18, AQUAVI 0.24, AQUAVI 0.3), the basal diet was formulated without any additional methionine addition; the other ten diets ( dl -Met 0.06, dl -Met 0.12, dl -Met 0.18, dl -Met 0.24, dl -Met 0.3; AQUAVI 0.06, AQUAVI 0.12, AQUAVI 0.18, AQUAVI 0.24, AQUAVI 0.3) were formulated with five graded levels of methionine with two different methionine sources of dl -Met and AQUAVI® Met-Met, respectively. Each diet was fed at a restricted rate to four groups of 30 shrimp for 63 days. The highest value of survival was observed with shrimp fed AQUAVI 0.24 diet, which was significantly higher than that of shrimp fed the basal, dl -Met 0.06 and dl -Met 0.18 (P 0.05). The highest values of growth performance (WG and SGR) were observed with shrimp fed AQUAVI 0.12 diet, which were significantly higher than those of shrimp fed the basal, dl -Met 0.06 and dl -Met 0.18 (P 0.05). A non-linear exponential regression model indicated that AQUAVI® Met-Met was found to be more bioavailable than dl -Met with calculated relative bioavailability values of 285.8%, 276.4% and 300.4% based on weight gain, specific growth rate and feed efficiency, respectively. These findings lead to the conclusion that differences in bioavailability do exist between sources of synthetic methionine, and AQUAVI® Met-Met is more available than DL-Met for L. vannamei.

Wafer-scale, CMOS compatible graphene transfer has been established for device fabrication and can be integrated into a conventional CMOS process flow back end of the line. In Part I of this paper, statistical analysis of graphene FET (GFET) devices fabricated on wafer scale is presented. Device yield is approximately 75% (for 4500 devices) measured in terms of the quality of the top gate, oxide layer, and graphene channel. Statistical evaluation of the device yield reveals that device failure occurs primarily during the graphene transfer step. In Part II of this paper, device statistics are further examined to reveal the primary mechanism behind device failure. The analysis from Part II suggests that significant improvements to device yield, variability, and performance can be achieved through mitigation of compressive strain introduced in the graphene layer during the graphene transfer process. The combined analyses from Parts I and II present an overview of mechanisms influencing GFET behavior as well as device yield. These mechanisms include residues on the graphene surface, tears, cracks, contact resistance at the graphene/metal interface, gate leakage as well as the effects of postprocessing.

Two-dimensional (2D) layered materials, in particular semiconducting transition metal dichalcogenides (TMDCs), are promising candidates for optoelectronic devices. The TMDC molybdenum disulfide $(\mathrm{MoS}_{2})$ has a bandgap dependent on the number of monolayers [1] and shows high optical absorption even in ultrathin and inherently flexible layers. TMDC photodetectors have been demonstrated [2], [3], however most 2D-based devices were built on rigid substrates using small exfoliated flakes. Alternatively, metal-organic vapor phase epitaxy (MOVPE) offers a highly scalable deposition method for homogeneous and reproducible TMDC layers [4]. Here, we present for the first time metal-semiconductor-metal (MSM) photodetectors with low bias voltage and high responsivity based on MOVPE films transferred onto flexible substrates.

Graphene / silicon (G/Si) heterostructures have been studied extensively in the past years for applications such as photodiodes, photodetectors and solar cells, with a growing focus on efficiency and performance. Here, a specific contact pattern scheme with interdigitated Schottky and graphene/insulator/silicon (GIS) structures is explored to experimentally demonstrate highly sensitive G/Si photodiodes. With the proposed design, an external quantum efficiency (EQE) of > 80 % is achieved for wavelengths ranging from 380 to 930 nm. A maximum EQE of 98% is observed at 850 nm, where the responsivity peaks to 635 mA/W, surpassing conventional Si p-n photodiodes. This efficiency is attributed to the highly effective collection of charge carriers photogenerated in Si under the GIS parts of the diodes. The experimental data is supported by numerical simulations of the diodes. Based on these results, a definition for the true active area in G/Si photodiodes is proposed, which may serve towards standardization of G/Si based optoelectronic devices., 24 pages, 5 figures

Graphene is an extremely promising material for emerging nanoelectromechanical systems (NEMS) and sensors, but the transfer from its growth substrate to silicon substrates remains manual and laborious. We report a novel method for the transfer of large-area chemical vapor deposited (CVD) graphene from copper foil to a target wafer by adhesive wafer bonding using bisbenzocyclobutene (BCB) as an intermediate adhesive layer. The use of conventional wafer bonding equipment enables the scalable transfer of graphene and the realization of both supported and suspended graphene devices on wafer-scale. Our method circumvents manual handling of graphene after release from its growth substrate and avoids polymeric carrier layers, a well-known source of contamination. Hence, the proposed process promises the transfer of graphene with high quality and repeatability.

Few-layer molybdenum disulfide (FL-MoS$_2$) films have been integrated into amorphous silicon (a-Si:H) pin photodetectors. To achieve this, vertical a-Si:H photodiodes were grown by plasma-enhanced chemical vapor deposition (PE-CVD) on top of large-scale synthesized and transferred homogeneous FL-MoS$_2$. This novel detector array exhibits long-term stability (more than six month) and outperforms conventional silicon-based pin photodetectors in the infrared range (IR, $\lambda$ = 2120 nm) in terms of sensitivities by up to 50 mAW$^{-1}$. Photodetectivities of up to 2 x 10$^{10}$ Jones and external quantum efficiencies of 3 % are achieved. The detectors further feature the additional functionality of bias-dependent responsivity switching between the different spectral ranges. The realization of such scalable detector arrays is an essential step towards pixelated and wavelength-selective sensors operating in the IR spectral range.

The experimental results of Metal-graphene (M-G) contact resistance R C have been investigated in-depth by means of Density Functional Theory (DFT). The simulations allowed us to build a consistent picture explaining the R C dependence on the metal contact materials employed in this work and on the applied back-gate voltage. In this respect, the M-G distance is paramount in determining the R C behavior.

In two feeding experiments the retention of supplemental guanidine acetic acid (GAA) in broilers was investigated. In both experiments, the same three treatments were used; the basal feed was supplemented with 0, 0.6, or 6.0 g GAA per kg of feed. While in a growth study (experiment 1) day-old, male Ross 308 broilers were fed diets for 35 days, these diets were fed for only 8 days to fistulated broilers 34 days of age in a balance study (experiment 2). Feeding 0.6 g/kg GAA did not improve growth performance whereas 6.0 g/kg GAA resulted in a reduction of feed consumption and consequently of weight gain (P ≤ 0.05). Feed conversion was not affected and was 1.48 to 1.49 in all treatments. Increasing levels of dietary GAA gradually increased the creatine concentration in breast muscle and liver tissues (P ≤ 0.05) indicating a transformation and retention of dietary GAA as creatine. In experiment 2 the non-supplemented basal diet allowed us to determine the endogenous GAA, creatine, and creatinine excretions. Accordingly, only small amounts of these metabolites were recovered in feces while they were much higher in urine. Increasing dietary GAA intake increased fecal and renal GAA, creatine, and creatinine excretion and was significant (P ≤ 0.05) at 6.0 g/kg dietary GAA compared to no or 0.6 g/kg GAA supplementation. The mean true fecal digestibility of GAA (99%) was unaffected by the level of supplemental GAA. Considering renal GAA excretions, true availability of supplemental GAA was reduced with increasing dose (83% vs. 71%; P ≤ 0.05). Taking into account creatine and creatinine excretions above those of the basal diet, as they are a consequence of increasing dietary supply, true availability of supplemental GAA shrank from 76% (0.6 g/kg GAA) to 46% (6.0 g/kg GAA; P ≤ 0.05). Changes in blood creatine and creatinine levels reflected the changes observed in the liver and muscle tissues and may suggest increased transport to excretion organs. Data from these experiment were used to estimate the creatine requirement.

A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso-nitrogenous (288 g kg(-1) protein) practical diets, with two DE levels (10.9 MJ kg(-1); 12.4 MJ kg(-1)) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg(-1)), were hand-fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 +/- 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high-DE diets were significantly higher than that of fish fed low-DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg(-1) diet (low-versus high-DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg(-1) diet, respectively; with cysteine 4.70 g kg(-1) diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high-DE diets required more methionine for maximum growth.

In this work, fabrication and characterisation of graphene photodiodes and transfer length method structures is presented. Graphene growth is carried out using a thermal chemical vapor deposition process on copper foils and subsequently transferred onto silicon-dioxide/silicon substrate. Comparison of electrical and optical characteristics of the photodiodes, which are fabricated on both n-type and p-type silicon, is shown. The photodiodes fabricated on n-type silicon show good rectifying behaviour when compared with photodiodes fabricated on p-type silicon. Spectral response of graphene photodiodes is measured to be less than 0.2 mAW-1 which is attributed to the light absorbance of 2.3% for single layer graphene. Transfer length method device structures are also fabricated and contact resistance is calculated and plotted as a function of spacing between the contacts. The calculated contact resistance (RcW) is 0.87 kΩ.µm. The latter structures are also characterised under various ambient conditions, before and after annealing. The value of contact resistance reduces from 0.87 kΩ.µm to 0.75 kΩ.µm after annealing. This reduction is attributed to the improvement in bonding between graphene and metal. Measurements under vacuum show an increase in contact resistance which is attributed to the removal of adsorbed water molecules on the surface on graphene. The sheet resistivity of graphene is calculated to be between 1.17 kΩ/□ and 3.67 kΩ/□.

A bottom-up chemical vapor deposition (CVD) process for the growth of graphene nanomesh films is demonstrated. The process relies on silicon nanospheres to block nucleation sites for graphene CVD on copper substrates. These spheres are formed in a self-organized way through silicon diffusion through a 5 $\mu$m copper layer on a silicon wafer coated with 400 nm of silicon nitride. The temperature during the growth process disintegrates the $Si_3$$N_4$ layer and silicon atoms diffuse to the copper surface, where they form the nanospheres. After graphene nanomesh growth, the Si nanospheres can be removed by a simple hydrofluoric acid etch, leaving holes in the graphene film. The nanomesh films have been successfully transferred to different substrates, including gas sensor test structures, and verified and characterized by Auger, TEM and SEM measurements. Electrical/gas-exposure measurements show a 2-fold increase in ammonia sensitivity compared to plain graphene sensors. This improvement can be explained by a higher adsorption site density (edge sites). This new method for nanopatterned graphene is scalable, inexpensive and can be carried out in standard semiconductor industry equipment. Furthermore, the substrates are reusable., Comment: 13 pages, 3 figures

Molybdenum disulfide (MoS2) is a semiconducting transition metal dichalcogenide material. This two-dimensional (2D) layered material has a band gap ranging from 1.3 eV in bulk form (indirect) to 1.88 eV as a monolayer (direct). The material has been suggested as a potential candidate for applications in nanoelectronics, optoelectronics and neuromorphic computing [1]–[4]. In this talk, the principles of scalable growth through thermal conversion of metals and metal-organic vapor phase growth will be discussed [5], [6]. These materials are then integrated into the silicon technology platform to demonstrate device applications. Conventional field effect transistors with MoS2 channels show promising characteristics. In addition, ion-based plasticity promises to enable memristive functionality on MoS2 devices. In particular, vertically aligned MoS2 layers allow the tuning of energy barriers at MoS2/semiconductor Schottky junctions through mobile ions [7], [8]. These ions (OH-) likely originate from catalytic splitting of water molecules. Spectral response measurements of MoS2 based devices provide insight into the band structure and beyond, as photodetectors based on MoS2/silicon/graphene and MoS2/amorphous silicon heterostructures show peculiar responsivity in the infrared regime [9]–[11]. Acknowledgements The authors acknowledge funding through the European Union’s Horizon 2020 research and innovation programme under grant agreements 785219 (Graphene Flagship) and 829035 (QUEFORMAL), the German BMBF grant NEUROTEC (16ES1134) and the DFG projects MOSTFLEX (407080863) and ULTIMOS2 (412113712). References [1] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically Thin MoS2: A New Direct-Gap Semiconductor,” Phys. Rev. Lett., vol. 105, no. 13, p. 136805, Sep. 2010. [2] B. Radisavljevic and A. Kis, “Mobility engineering and a metal–insulator transition in monolayer MoS2,” Nat. Mater., vol. 12, no. 9, pp. 815–820, Sep. 2013. [3] A. Bablich, S. Kataria, and M. C. Lemme, “Graphene and Two-Dimensional Materials for Optoelectronic Applications,” Electronics, vol. 5, no. 1, p. 13, Mar. 2016. [4] V. K. Sangwan et al., “Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide,” Nature, vol. 554, no. 7693, pp. 500–504, Feb. 2018. [5] S. Kataria et al., “Growth-Induced Strain in Chemical Vapor Deposited Monolayer MoS2: Experimental and Theoretical Investigation,” Adv. Mater. Interfaces, vol. 4, no. 17, p. 1700031, Sep. 2017. [6] M. Marx et al., “Large-area MoS2 deposition via MOVPE,” J. Cryst. Growth, vol. 464, pp. 100–104, Apr. 2017. [7] M. Belete et al., “Dielectric Properties and Ion Transport in Layered MoS2 Grown by Vapor-Phase Sulfurization for Potential Applications in Nanoelectronics,” ACS Appl. Nano Mater., vol. 1, no. 11, pp. 6197–6204, Nov. 2018. [8] M. Belete et al., “Nonvolatile Resistive Switching in Nanocrystalline Molybdenum Disulfide with Ion-Based Plasticity,” arXiv:1911.06032, 2019. [9] C. Yim et al., “Heterojunction Hybrid Devices from Vapor Phase Grown MoS2,” Sci. Rep., vol. 4, Jun. 2014. [10] M. Belete et al., “Large Scale MoS2/Si Photodiodes with Graphene Transparent Electrodes,” presented at the European Solid-State Device Research Conference (ESSDERC), Krakow, Poland, 2019. [11] A. Bablich et al., “Few-Layer MoS2/a-Si:H Heterojunction Pin-Photodiodes for Extended Infrared Detection,” ACS Photonics, vol. 6, no. 6, pp. 1372–1378, Jun. 2019.

Rapid, simple, and large-area imaging of grain boundaries in CVD graphene placed on a SiO2 surface by vapor HF exposure., The shape and density of grain boundary defects in graphene strongly influence its electrical, mechanical, and chemical properties. However, it is difficult and elaborate to gain information about the large-area distribution of grain boundary defects in graphene. An approach is presented that allows fast visualization of the large-area distribution of grain boundary–based line defects in chemical vapor deposition graphene after transferring graphene from the original copper substrate to a silicon dioxide surface. The approach is based on exposing graphene to vapor hydrofluoric acid (VHF), causing partial etching of the silicon dioxide underneath the graphene as VHF diffuses through graphene defects. The defects can then be identified using optical microscopy, scanning electron microscopy, or Raman spectroscopy. The methodology enables simple evaluation of the grain sizes in polycrystalline graphene and can therefore be a valuable procedure for optimizing graphene synthesis processes.

2018 76th Device Research Conference (DRC) : 24-27 June 2018 / [IEEE Electron Device Society (EDS) - ​technical co-sponsor ; Materials Research Society (MRS) - co-sponsor] 2018 76th Device Research Conference, DRC, Santa Barbara, CA, USA, 24 Jun 2018 - 27 Jun 2018; Piscataway, NJ : IEEE 2 Seiten (2018). doi:10.1109/DRC.2018.8442221, Published by IEEE, Piscataway, NJ

2018 76th Device Research Conference (DRC) : 24-27 June 2018 / [IEEE Electron Device Society (EDS) - ​technical co-sponsor ; Materials Research Society (MRS) - co-sponsor] 76th Device Research Conference, DRC 2018, Santa Barbara, CA, USA, 24 Jun 2018 - 27 Jun 2018; Piscataway, NJ : IEEE 2 Seiten (2018). doi:10.1109/DRC.2018.8442228, Published by IEEE, Piscataway, NJ

We report on the fabrication and characterization of field effect transistors (FETs) based on chemical vapor deposited (CVD) graphene encapsulated between few layer CVD boron nitride (BN) sheets with complementary metal oxide semiconductor (CMOS) compatible nickel edge contacts. Non-contact Tera-hertz time domain spectroscopy (THz-TDS) of large-area BN/graphene/BN (BN/G/BN) stacks reveals average sheet conductivity >1 mS/sq and average mobility of 2500 cm$^{2}$/Vs. Improved output conductance is observed in direct current (DC) measurements under ambient conditions, indicating potential for radio-frequency (RF) applications. Moreover, we report a maximum voltage gain of 6 dB from a low frequency signal amplifier circuit. RF characterization of the GFETs yields an f$_{T}$ x L$_{g}$ product of 2.64 GHz$��$m and an f$_{Max}$ x L$_{g}$ product of 5.88 GHz$��$m. This study presents for the first time THz-TDS usage in combination with other characterization methods for device performance assessment on BN/G/BN stacks. The results serve as a step towards scalable, all CVD 2D material-based FETs for CMOS compatible future nanoelectronic circuit architectures., 6 pages

In vitro cardiac models able to mimic the fibrotic process are paramount to develop an effective anti-fibrosis therapy that can regulate fibroblast behaviour upon myocardial injury. In previously developed in vitro models, typical fibrosis features were induced by using scar-like stiffness substrates and/or potent morphogen supplementation in monolayer cultures. In our model, we aimed to mimic in vitro a fibrosis-like environment by applying cyclic stretching of cardiac fibroblasts embedded in three-dimensional fibrin-hydrogels alone. Using a microfluidic device capable of delivering controlled cyclic mechanical stretching (10% strain at 1 Hz), some of the main fibrosis hallmarks were successfully reproduced in 7 days. Cyclic strain indeed increased cell proliferation, extracellular matrix (ECM) deposition (e.g. type-I-collagen, fibronectin) and its stiffness, forming a scar-like tissue with superior quality compared to the supplementation of TGFβ1 alone. Taken together, the observed findings resemble some of the key steps in the formation of a scar: (i) early fibroblast proliferation, (ii) later phenotype switch into myofibroblasts, (iii) ECM deposition and (iv) stiffening. This in vitro scar-on-a-chip model represents a big step forward to investigate the early mechanisms possibly leading later to fibrosis without any possible confounding supplementation of exogenous potent morphogens.

Summary Cardiomyocytes (CMs) generated from human induced pluripotent stem cells (hiPSCs) are under investigation for their suitability as human models in preclinical drug development. Antiarrhythmic drug development focuses on atrial biology for the treatment of atrial fibrillation. Here we used recent retinoic acid-based protocols to generate atrial CMs from hiPSCs and establish right atrial engineered heart tissue (RA-EHT) as a 3D model of human atrium. EHT from standard protocol-derived hiPSC-CMs (Ctrl-EHT) and intact human muscle strips served as comparators. RA-EHT exhibited higher mRNA and protein concentrations of atrial-selective markers, faster contraction kinetics, lower force generation, shorter action potential duration, and higher repolarization fraction than Ctrl-EHTs. In addition, RA-EHTs but not Ctrl-EHTs responded to pharmacological manipulation of atrial-selective potassium currents. RA- and Ctrl-EHTs’ behavior reflected differences between human atrial and ventricular muscle preparations. Taken together, RA-EHT is a model of human atrium that may be useful in preclinical drug screening., Graphical Abstract, Highlights • Retinoic acid induced differentiation of hiPSCs into atrial-like myocytes • 3D engineered heart tissue format favored atrial specificity compared with 2D culture • Atrial-like engineered heart tissue can be used as a model of human atrium, Lemme et al. developed a human, atrial-like engineered heart tissue from hiPSCs that could be used as an in vitro model of the human atrium to evaluate selectivity of novel ion channel blockers for atrial fibrillation.

Platinum diselenide (PtSe2) is a group-10 transition metal dichalcogenide (TMD) that has unique electronic properties, in particular a semimetal-to-semiconductor transition when going from bulk to monolayer form. We report on vertical hybrid Schottky barrier diodes (SBDs) of two-dimensional (2D) PtSe2 thin films on crystalline n-type silicon. The diodes have been fabricated by transferring large-scale layered PtSe2 films, synthesized by thermally assisted conversion of predeposited Pt films at back-end-of-the-line CMOS compatible temperatures, onto SiO2/Si substrates. The diodes exhibit obvious rectifying behavior with a photoresponse under illumination. Spectral response analysis reveals a maximum responsivity of 490 mA/W at photon energies above the Si bandgap and relatively weak responsivity, in the range of 0.1–1.5 mA/W, at photon energies below the Si bandgap. In particular, the photoresponsivity of PtSe2 in infrared allows PtSe2 to be utilized as an absorber of infrared light with tunable sensitivity. The results of our study indicate that PtSe2 is a promising option for the development of infrared absorbers and detectors for optoelectronics applications with low-temperature processing conditions.

2018 76th Device Research Conference (DRC) : 24-27 June 2018 / [IEEE Electron Device Society (EDS) - ​technical co-sponsor ; Materials Research Society (MRS) - co-sponsor] 76th Device Research Conference, DRC 2018, Santa Barbara, CA, USA, 24 Jun 2018 - 27 Jun 2018; Piscataway, NJ : IEEE (2018). doi:10.1109/DRC.2018.8442264, Published by IEEE, Piscataway, NJ

We demonstrate resistive humidity sensing using a single-layer graphene patch placed on top of a SiO2 layer on a Si wafer., We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further investigate the sensitivity of the graphene devices towards water vapor. The interaction between the electrostatic dipole moment of the water and the impurity bands in the SiO2 substrate leads to electrostatic doping of the graphene layer. The proposed graphene sensor provides rapid response direct electrical readout and is compatible with back end of the line (BEOL) integration on top of CMOS-based integrated circuits.