bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Hybrid III-V/Si CMOS Technology Platform: From Materials for Logic to Integrated RF and Photonics
Authors: Czornomaz Lukas 
Published: February 2020

In the past few years, tremendous progress has been achieved in the integration of III-V compound semiconductors on a Si CMOS platform as high-mobility channel materials are foreseen as potential candidates to replace Si channels in advanced CMOS technology nodes. Beyond CMOS scaling, the integration of III-V materials and devices on a Si CMOS platform enables bringing their traditional enhanced functionalities to the chip level: high-speed low-noise RF as well as lasers and sensitive photodetectors.
In this presentation, we will review the technologies that we developed to monolithically integrate III-V materials on Si by direct epitaxy in empty oxide cavities or by direct wafer bonding. We will show that record logic n-MOSFET performance can be achieved for ultra-scaled gate lengths (Lg = 13nm), that hybrid III-V/Si(Ge) CMOS functionality can be obtained (inverters, 6T-SRAMs). We will then highlight how 3D monolithic integration enables seamless integration of III-V functionalities on top of Si CMOS front-end for logic as well as for RF and Photonics.
IR-Photodetector Fabrication on Suspended Gesn Thin Layers
Authors: Abedin Ahmad , Garidis Konstantinos , Hellström Per-Erik , Ostling Mikael 
Published: February 2020

The energy bandgap (Eg) of Ge effectively shifts toward lower energies by alloying with Sn atoms. Strain-relaxed (SR) GeSn layers with more than 8% Sn content assumes a direct bandgap and can be potentially used for highly-sensitive photodetectors for the short-wavelength infrared (SWIR) region (Eg<0.6 eV). However, the epitaxial growth of SR GeSn alloys with high crystalline quality is challenging due to the large lattice mismatch with both Si and SR Ge [1]. One method for fabricating SR GeSn is based on the growth of compressively strained GeSn layers on SR Ge and releasing the strain by selective Ge under-etching [2]. In this study, a suspended IR-photodetector was fabricated using strain-relaxed Ge0.9Sn0.1 layer through microstructuring and Ge under-etching.
The GeSn layers were grown on a Ge-buffered Si wafer [3] in a reduced pressure chemical vapor deposition tool using digermane and tin tetrachloride as Ge and Sn precursors. Two batches of detectors were fabricated; one based on GeSn on Ge and the other one based on suspended GeSn layers. Photolithography and ICP dry etching were used for patterning the detectors and the Ge underneath were removed by anisotropic selective etching using CF4 gas. XRD and RBS measurements indicate Sn contents of more than 10% without any Sn out diffusion. Raman spectroscopy shows the strain relaxation through Ge under-etching and layer release. The temperature dependence dependent photoluminescence spectra shown in Fig. 1 is in accordance with a direct band gap transitions of the GeSn layers around 0.5 eV. The effects of layer suspension on the absorption spectra and the photo response of the detectors will be discussed in the presentation.
Fig. 1) Temperature dependence photoluminescence spectra of GeSn layer with 12% Sn content

Acknowledgements:

This work was supported by the Swedish Foundation for Strategic Research (SSF) and Vetenskapsrådet (VR).

References:

[1] S. Wirths, R. Geiger, N. von den Driesch, G. Mussler, T. Stoica, S. Mantl, Z. Ikonic, M. Luysberg, S. Chiussi, J.M.Hartmann, H. Sigg, J. Faist, D. Buca & D. Grützmacher, Nature Photonics volume 9, pages 88–92 (2015).
[2] S. Gupta, R. Chen, Y. Huang, Y. Kim, E. Sanchez, J. S. Harris, and K. C. Saraswat, Nano Letters 13 (8), 3783-3790 (2013).
[3] A. Abedin, A. Asadollahi, K. Garidis, P.-E. Hellström and M. Östling, ECS Trans. volume 75, issue 8, 615-621 (2016).

Figure 1
Improving the Performance of the Optical Antenna for Integrated LIDAR with Optical Phased Arrays through High Contrast Grating Structure on SOI Substrate
Authors: Wang Pengfei , Li Zhaosong , Yu Hongyan , Li Yajie , Tang Qiang , Zhao Wu , Zhou Xuliang , Chen Weixi , Zhang Yejin , Pan Jiaoqing 
Published: February 2020

With the development of automatic driving and remote sensing technology, light detection and ranging (LIDAR) has attracted more attentions. The optical phased arrays in silicon photonics have became one of the major solutions of LIDAR due to its low material cost, high integration, and compatibility with CMOS technology. However, most of the optical antennas used by LIDAR are directly etched second-order gratings on the array waveguides, which makes the emission efficiency very low, and a large part of the energy is wasted by the side lobes and grating lobes. Therefore, improving the antenna emission efficiency and its energy utilization has become the key solution to improve the performance of phased-array LIDAR systems.
In this paper, a novel optical antenna for integrated LIDAR with optical phased arrays is proposed and simulated. The high contrast grating (HCG) structure is used to achieve extremely efficient emission. The basic structure of the optical antenna consists of a 220nm Si plane waveguide at the top-Si layer of SOI substrate, a 110nm SiO2 gap layer, and a 463nm Polysilicon layer. The HCG period is 1.228μm and duty cycle is 0.388, and it is etched at the Polysilicon layer.
The proposed optical antenna has improved emission efficiency, energy utilization, and achievable scanning range. It is possible to increase emission efficiency significantly by the resonance properties of the HCG. 81.6% emission efficiency of the optical antenna is obtained with background suppression of 28.4 dB at 1550 nm. Moreover, the optical antenna can achieve more than 50% emission efficiency in the wavelength range of 1484 nm to 1609 nm. ±34.82°×18.99° scanning range was realized in lateral direction and longitudinal direction, respectively, by changing the phase difference between adjacent waveguides and the wavelength from 1480 nm to 1580 nm. In lateral direction, the scanning range achieved by the proposed optical antenna is 1.54 times larger than that of an arrayed waveguide grating with the same size. In longitudinal direction, the proposed optical antenna can achieve substantially the same scanning range as the arrayed waveguide grating.

Figure 1
Thermal Transport across a Semiconductor/Semiconductor Interface: A First-Principles-Based Approach
Authors: Maassen Jesse , Askarpour Vahid 
Published: February 2020

Controlling heat flow across material heterojunctions is important for thermoelectrics and thermal management of electronic devices. A clear physical understanding of what transport mechanism dominates near an interface can help benefit technology. We present a theoretical investigation of phonon transport across a semiconductor/semiconductor interface, specifically Si/Ge, and demonstrate how inelastic scattering and non-equilibrium effects play a key role.
We treat phonon transport with the McKelvey-Shockley flux method, which is efficient, captures ballistic and non-equilibrium effects, inelastic scattering, and has shown excellent agreement with the more computationally-demanding Boltzmann equation. The Si and Ge phonon dispersions and 3-phonon scattering rates, serving as input for the transport modeling, are calculated from first-principles. The results show that, while the maximum phonon frequency in Si is nearly double that of Ge, significant heat currents are carried by the high-frequency Si phonons above the Ge cutoff. When approaching the interface, inelastic scattering redistributes energy to the phonon frequencies that can transfer elastically across the Si/Ge junction. We explain how this collective reorganization of phonons is driven by non-equilibrium effects near the interface. We also include a model for the contact resistance of an ideal interface, that depends on both phonon dispersions, which provides a lower limit for a given material combination. These results help provide clear physical insights into what controls phonon transport at semiconductor/semiconductor interfaces.
(Invited) Chemical Design for Transparent Bipolar Semiconductors
Authors: Iimura Soshi , Hosono Hideo 
Published: February 2020

Transparent bipolar semiconductors (TBSCs) are in demand for transparent electronics to serve as the basis for next generation optoelectronic devices. However, the poor carrier controllability in wide-bandgap materials makes the realization of a bipolar nature difficult. Only two materials, CuInO2 and SnO, have been reported as TBSCs. To satisfy demand for the coexistence of transparency and bipolarity, we propose a design concept with three strategies; choice of early transition metals (eTM) such as Y3+ and Zr4+ for improving controllability of carrier doping, design of chemical bonds to obtain an appropriate band structure for bipolar doping, and use of a forbidden band-edge transition to retain transparency. This approach is verified through a practical examination of a candidate material, tetragonal ZrOS, which is chosen by following the criteria [1]. ZrOS exhibits an excellent controllability of the electrical conductivity (10−7 -10−2 S cm−1), p- or n-type nature with ∼10−2 S cm−1 by Y or F doping, respectively, and optically wide gap (below 10−4 cm−1 up to ∼2.5 eV). This concept provides a new kind of TBSC based on eTM ionic compounds. In this talk, we also show an interesting phenomenon of other eTM semiconductor: carrier polarity inversion via doping-induced polymorph change in LaSeF [2].
References
[1] T. Arai, S. Iimura, J. Kim, Y. Toda, S. Ueda, and H. Hosono, J. Am. Chem. Soc.
139, 17175-17180 (2017).
[2] T. Arai, S. Iimura, and H. Hosono, Chem. Matter.
30, 597-601 (2018).

Figure 1
(Invited) Hydrogen-Related Trap States Induced during Fabrication Process and Annealing Effects in Amorphous in-Ga-Zn-O Thin Film Transistors
Authors: Ochi Mototaka , Hino Aya , Goto Hiroshi , Hayashi Kazushi , Kugimiya Toshihiro 
Published: February 2020

Transparent amorphous oxide semiconductors (TAOSs) such as amorphous In-Ga-Zn-O (a-IGZO) are superior to the conventional semiconducting materials used in flat-panel displays (FPDs) because they have the advantages of high electron mobility, good uniformity, and a simple manufacturing process based on matured sputtering techniques [1]. To apply TAOS thin-film transistors (TFTs) to the mass production of next-generation displays, the stress stability during the a-IGZO TFT operation is a crucial issue that must be resolved.
It has been reported that the concentration of the hydrogen atoms in the a-IGZO is huge and the diffusion coefficient of hydrogen is two orders of magnitude larger than that of oxygen [2]. It means that hydrogen atoms easily diffuse into the channel region of the a-IGZO TFTs from hydrogen-containing layers such as a passivation layer (PV) during the fabrication. Hydrogen atoms also easily absorb to the channel region during the fabrication. Therefore, clarification of the effect of hydrogen on the electronic properties of the a-IGZO is particularly important to improve the TFT performance such as various stress stabilities against negative bias thermal illumination stress (NBTIS), negative bias thermal stress (NBTS) and positive bias thermal stress (PBTS).
The hump-shaped variation of the transfer curves under the NBTIS test was observed in both a-IGZO etch-stop layer (ESL)-type and back channel etch (BCE)-type TFTs. According to the results of photo-induced transient spectroscopy (PITS) analysis, it was observed that the density of hydrogen-related traps in the a-IGZO thin film was changed with the increase and/or decrease of hydrogen incorporated by the TFT manufacturing process [3, 4]. In this presentation, the impact of hydrogen-related trap levels on stress reliability with humps will be reviewed. Furthermore, the parallel-shaped variation of the transfer curves under the NBTS and PBTS test changed depending on the temperature of post-process annealing. It is believed that these behaviors are caused by interface defects due to dissociation and diffusion of hydrogen atoms at the interface [5, 6].
[1] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, Nature Vol. 432, pp. 488-492 (2004).
[2] K. Nomura, T. Kamiya, and H. Hosono, ECS J. Solid State Sci. Technol. Vol. 2, No. 1, pp. 5-8 (2013).
[3] K. Hayashi, M. Ochi, A. Hino, H. Tao, H. Goto, and T. Kugimiya, Jpn. J. Appl. Phys. 56, 03BB02 (2017).
[4] M. Ochi, A. Hino, H. Goto, K. Hayashi, and T. Kugimiya, ECS J. Solid State Sci. Technol. 6, P247 (2017).
[5] K. Hayashi, M. Ochi, A. Hino, H. Tao, H. Goto, and T. Kugimiya, Proc. IDW ’17, pp. 320-323 (2017).
[6] M. Ochi, A. Hino, H. Goto, K. Hayashi, and T. Kugimiya, Jpn. J. Appl. Phys. 57, 02CB06 (2018).

Figure 1
Integrated Taste Sensor Circuit with Oxide TFT
Authors: Han Ye Lin , Kang In Hye , Hwang Sang Ho , Baek Yeong Jo , Bae Byung Seong 
Published: February 2020

Among the sensors that imitating the human five senses, the visual sensors are commercialized as CIS (CMOS Image Sensor) and CCD (Charge Coupled Device), and tactile sensor are partly commercialized as a touch sensor. Also, auditory sensor is commercialized as a microphone. However, the smell and taste sensors are still under development.
If the taste is sensed electrically, it is possible to obtain standard taste information. For portable applications a small size taste sensor system is required and a suitable technology for manufacturing such a highly sensitive small-sized sensor is semiconductor technology. Conventional taste sensors require a large amount of test material because they are large in volume. Also require expensive equipment and not suitable for portable device.
Various types of biosensors have been developed to overcome these drawbacks. The FET-type biosensor has advantages of miniaturization and standardization by integrating the sensor and the circuit by utilizing the integrated circuit manufacturing process. Among the devices capable of integrated circuits, thin film transistors with oxide semiconductor materials are one of the candidates having a simpler process than the LTPS TFT and a higher field effect mobility than the a-Si TFT.
Depending on the taste substances, the emitter current in the FET sensor changes. Each taste solution and lipid sensing membrane have different sensing principles. For example, a sourness, saltiness, or sweetness solution are electrochemical reactions in which specific ions are assembled near the lipid sensing membrane by electrical attraction, the bitterness solution is hydrophobic and certain molecules are absorbed by the lipid sensing membrane Hydrophobic binding. Those reactions induce potential changes of the floating gate and changes the current of the device.
As the concentration of the taste substances increases, the current of the transistor increases. And each solution has different values depending on the lipid sensing membrane. In this paper, an oxide transistor-based amplifier is designed for a taste sensor. We designed an amplifier that works well even when the size of the transistor changes and the threshold voltage changes.
Usually amplifier circuit require the optimum operation bias, which make the circuit complicated. However, in this paper we proposed a cascaded Class A amplifier which uses self-bias unit instead of voltage divider by resistors as shown in figure. In this circuit, T3 is a taste sensing transistor. Sensing signal is amplified by supply the alternation voltage through capacitor. The alternative way is to use T4 as a taste sensor. The amplification gains for different location of the sensor were compared.

Figure 1
Vertical Channel a-IGZO Thin Film Transistors Using Thin Gate Dielectric
Authors: Baek Yeong Jo , Hwang Sang Ho , Lee Sang Min , Han Ye Lin , Kang In Hye , Bae Byung Seong 
Published: February 2020

Oxide thin film transistors (TFTs) are widely used as backplane for displays such as active matrix organic light emitting diode display and active matrix liquid crystal display. And also, it can be used in many applications such as sensor and wearable devices which require small power consumption. For low power consumption, the operation voltage should be decreased and the vertical structure TFT is a candidate due to short channel length. In this study, we proposed a vertical structure TFTs using a thin gate dielectric.
In this experiment, a vertical structure TFTs with a channel formed on the vertical sidewall of the gate electrode and a channel length controlled by the thickness of the gate electrode is proposed. The channel length was adjusted by the thickness of the gate electrode in the vertical TFTs developed in this paper. Figure 1 shows the fabricated vertical a-IGZO TFT developed in this study.
This vertical TFTs has the feature of controlling the channel length by the thickness of the gate electrode and can achieve short channel length easily, which is useful for low driving voltage. To reduce the gate voltage also, the thin gate dielectric was used. Since the very thin gate insulator was used, low threshold voltage was obtained, and low voltage driving was possible.

Figure 1
Optical Properties of Transition Metal Dichalcogenide MoS2thin Films Synthesized By Atomic Layer Deposition
Authors: Zeng Min , Lin Pengtao , McCleese Christopher , Kolodziej Charles , Zhang Kai , Burda Clemens , Li Qiliang , Baumgart Helmut 
Published: February 2020

Transition metal dichalcogenides (TMDCs), such as MoS2, WS2, WSe2 and MoSe2, exhibit a special structure in which a transition metal layer sandwiched between two chalcogen atomic layers. The in-plane covalent bonds between neighboring layer are strong and interplane van der Waals forces which keep the layer together are relatively weak. Especially, the monolayers commonly called as two-dimensional (2D) materials, are highly attractive due to their unique and tunable material properties. Therefore, the 2D TMDCs has promising potentials for the application of sensors, filed effect transistors, opto-electronics, piezoelectric devices, energy storage and hydrogen generation.
Recently, monolayer or few-layer TMDC films have been fabricated by many techniques, such as exfoliation, pulsed laser deposition (PLD), chemical vapor deposition (CVD). However, very little is known about atomic layer deposition (ALD) synthesis of 2D films and there are very only few references. ALD technique exhibits self-limiting atomic layer reactions in each introduced ALD cycle. ALD is the ability to control film thickness at angstrom level. Therefore, it offers better control of parameters like the composition, stoichiometry, uniformity and sharp interface. Furthermore, ALD also can be used to deposit conformal film onto very complex structures.
For this study MoS2 thin films have been prepared on silicon with native oxide and quartz substrates by Atomic Layer Deposition using Molybdenum hexacarbonyl (Mo(CO)6) and dimethyldisulfide (CH3SSCH3, DMDS) as the chemical ALD precursors for Molybdenum and Sulfur, respectively. For our experiments, 20 sccm N2 was used as a carrier gas flow for the precursors. This carrier gas flow enabled proper transport of precursors from the precursor cylinder to the reaction chamber. The growth temperature was set at 200, 230 and 250 oC. The chamber base pressure was kept at 40 mTorr. The crystallinity of as-deposited MoS2 thin film could be improved by post-annealing under saturated sulfur vapor. The Raman spectroscopy analysis show the MoS2 thin films the characteristic of E12g and A1g Raman modes. Multilayered MoS2 films were investigated with femtosecond laser pump-probe spectroscopy for the effects of increasing layer thickness on the electronic relaxation dynamics. It was found that the decay processes and valence band splitting are in accord with the known energy scheme for MoS2 thin films. A band gap of about 1.8 eV of MoS2 thin film is in the range of 1.1 eV (bulk MoS2) to 1.9 eV (monolayer MoS2). The band gap of ALD MoS2 thin films is much closer to the monolayer limit than the bulk limit.
Origami Microfluidic CD
Authors: Aeinehvand MohammadMahdi , Sosa Silva Patricia , Bosques Palomo Beatriz , Valencia Velarde Flor Helena , Diaz Armas Gladys , Caballero Saldivar Eduardo , Madou Marc J , Martinez-Chapa Sergio Omar 
Published: February 2020

Employing the centrifugal force for liquid displacement in bioanalytical compact discs (CDs) is becoming more popular for academic and industry applications. Pseudo forces that are controlled by a low-cost spindle motor enables the simultaneous manipulation of several liquids on the microfluidic CD. For this reason, centrifugal microfluidic platforms are considered more robust for extreme point of care (ePOC) applications when compared to stationary microfluidic systems that work with mechanical liquids pumps (e.g., syringe pump). However, the fabrication of microfluidic CDs requires expensive and bulky equipment (e.g., router or laser CNC) that cannot be implemented at ePOC and point of need (PON). To cope with this limitation, we have introduced a rapid microfluidic CD fabrication technique using only a low-cost cutter plotter [1]. The CDs were made through assembly of thin PVC and double-sided pressure sensitive adhesive (PSA) layers that were cut by the plotter machine. However, the technique yet required careful assembly of several disc layers, and the double-sided PSA is an expensive material and not widely available. In this article, we introduce a new origami CD fabrication process using only one type of material, a cutter plotter and a laminating machine. The origami CDs fabrication process prevents the need for PSA film and the tedious/sensitive CD assembly procedure. Therefore, the origami CDs facilitates onsite development of automated diagnosis test at ePOC and PON with minimum and widely available material and equipment. In addition to the origami CD fabrication process, this study includes the characterization of different microchannels made by the cutter plotter blade. Finally, as an application of the CD fabrication technique we developed an origami CD for automated serial dilution that is required for a wide range of bioanalytical applications such as microbial counting and multiplexed assay.
[1] M.M. Aeinehvand, P. Magaña, M.S. Aeinehvand, O. Aguilar, M.J. Madou, S.O. Martinez-Chapa, Ultra-rapid and low-cost fabrication of centrifugal microfluidic platforms with active mechanical valves, RSC Adv. 7 (2017) 55400–55407. doi:10.1039/C7RA11532F.