Showing papers presented at "International Meeting for Future of Electron Devices, Kansai in 2011"
19 May 2011
TL;DR: In this paper, the design concept of threshold voltage for ultralow-voltage (V dd = 0.4V) operation of thin-buried oxide (SOTB) CMOS is presented.
Abstract: The silicon on thin buried oxide (SOTB) CMOS is suited for ultralow-voltage operation of CMOS circuits, that is required for drastic power reduction of LSIs because of its small variability and adaptive back bias controllability. In this study, we show that the design concept of threshold voltage for ultralow-voltage (V dd =0.4V) operation of SOTB. To achieve a good trade-off of I on and I off , gate work function (Ф WF ) should be controlled at 4.25–4.35eV and 4.90–5.05eV for N- and P-type MOS-FETs (NMOS and PMOS), respectively. Moreover, higher N sub is preferable for increasing I on . Our optimized design achieved that I on values 170 and 89 µA/µm at I off values of 5.6 and 7.8 pA/µm for NMOS and PMOS, respectively. This result indicates that the 0.4-v operation is possible without paying significant speed penalty from the conventional 1-V operation.
6 citations
19 May 2011
TL;DR: The feasibility of alcohol intake detection via bio-impedance modulation through pulsation modulation is examined; the pulsation appearing in the artery is captured.
Abstract: This paper pays attention to the bio-impedance of the human body, and considers the impact of alcohol intake on the bio-impedance. We examine the feasibility of alcohol intake detection via bio-impedance modulation; we capture the pulsation appearing in the artery.
6 citations
19 May 2011
TL;DR: In this article, a Si wafer is directly bonded to a single-crystalline 6H-SiC wafer and a Si MOSFET is fabricated on the Si-on-Si c wafer.
Abstract: We developed an engineered wafer, a Si-on-SiC wafer, in which a Si wafer is directly bonded to single-crystalline 6H-SiC. We demonstrated a remarkable improvement in heat dissipation performance and a 60% reduction in the self-heating effect of Si MOSFET fabricated on Si-on-SiC wafer. Although a leakage current via the bonded interface is a concern in the device operation for the directly bonded Si-on-SiC wafer, a distinct degradation of leakage current is not observed in range of Si thickness between 2 and 13 µm.
6 citations
19 May 2011
TL;DR: In this paper, single-crystals of a ZnO thin film, a znO bulk, and a GaN bulk for reference were irradiated by 8 MeV protons at a wide range of the fluence from 2×1013 to 1×1017 p/cm2.
Abstract: Zinc oxide (ZnO) is a potential semiconductor to exhibit high radiation hardness since large threshold displacement energy for damage can be expected due to the small unit-cell volume and large bandgap energy. To study the radiation hardness, single-crystals of a ZnO thin film, a ZnO bulk, and a GaN bulk for reference were irradiated by 8 MeV protons at a wide range of the fluence from 2×1013 to 1×1017 p/cm2. For the ZnO thin film, a rapid decrease of luminescence intensity followed by an increase of electrical resistance was observed at larger fluences than ∼5×1014 p/cm2. This threshold fluence was found to be much larger and larger than those of GaN and ZnO bulk crystals, respectively, indicating that ZnO is harder than GaN, and thin film is harder than the bulk material.
5 citations
19 May 2011
TL;DR: The pneumatic balloon actuator (PBA) based surgical tool for a retinal pigment epithelium transplantation is reported to demonstrate advantages of S3 micromachine.
Abstract: This paper describes small, soft, and safe (S3) micromachine for minimally invasive medicine. We have developed pneumatic balloon actuator (PBA) as S3 micromachine. The PBA is applied to a retractor for spacing in front of the endoscope. The PBA based surgical tool for a retinal pigment epithelium transplantation is also reported to demonstrate advantages of S3 micromachine.
4 citations
19 May 2011
TL;DR: In this paper, the minority carrier diffusion and recombination process of nano-scale Si wire pn junction device with the aid of 3D device simulations is examined with a 3D simulator.
Abstract: This paper examines the minority carrier diffusion and recombination process of nano-scale Si wire pn junction device with the aid of 3-D device simulations.
4 citations
19 May 2011
TL;DR: In this paper, a theoretical study of the electronic and optical properties of the intermediate band solar cells (IBSCs) formed by an InAs/GaAs QD arrays is presented.
Abstract: Intermediate band solar cells (IBSCs) have been proposed as highly efficient third generation photovoltaic devices. Quantum dot (QD) arrays produce mini-bands that are separated by a region of zero density of states from other states in the conduction band. Additional absorption from the valence band to the IB and the IB to the conduction band allows two photons with energies below the energy gap to be harvested in generating one electron-hole pair. We present a theoretical study of the electronic and optical properties of the IB formed by an InAs/GaAs QD arrays. The calculations are based on effective-mass approximation and finite element method. Theoretical results of the mini-band width variation with the period of the QD arrays in the z direction are presented.
3 citations
19 May 2011
TL;DR: In this paper, a flexible ZnO thin-film transistors (TFTs) using multilayer oxide buffer layers were fabricated by pulsed laser deposition (PLD) at room temperature.
Abstract: We report on the fabrication and characterization of flexible ZnO thin-film transistors (TFTs) using multilayer oxide buffer layers. ZnO-TFTs on polyethylene napthalate (PEN) substrates were fabricated by pulsed laser deposition (PLD) at room temperature (RT). ZnO films were characterized by Hall effect measurements. The electron mobility and the carrier density were 52.4 cm2/Vs and 3.2×1017 cm−3. Top-gate-type TFTs were fabricated from a thin film of HfO 2 dielectric as a high-k material gate insulator. A transconductance, g m , of 1.7 mS/mm, an on/off-current ratio of 2.4×106 and a threshold voltage, V th , of −1.2 V were achieved for a ZnO TFT with a SiO 2 /TiO 2 buffer layer.
3 citations
19 May 2011
TL;DR: In this paper, an n-GaN metal-oxide-semiconductor (MOS) diode was fabricated using atomic layer deposited (ALD) Al 2 O 3, prior to which the surface was treated with (NH 4 ) 2 S solution.
Abstract: In this paper, an n-GaN metal-oxide-semiconductor (MOS) diode was fabricated using atomic layer deposited (ALD) Al 2 O 3 . Prior to Al 2 O 3 deposition, the n-GaN surface was treated with (NH 4 ) 2 S solution. As a result, interface state density of the treated n/n+-GaN MOS diode was significantly reduced compared to that without (NH 4 ) 2 S treatment.
3 citations
19 May 2011
TL;DR: In this article, the electronic structure of vertically stacked cubic quantum dots for the purpose of exploring the efficient design of quantum dot intermediate solar cells was studied and the dependence of the miniband levels and widths on the number of quantum dots as well as the inter-dot spacing was analyzed.
Abstract: We study the electronic structure of vertically stacked cubic quantum dots for the purpose of exploring the efficient design of quantum dot intermediate solar cells. We analyzed the dependence of the miniband levels and widths on the number of quantum dots as well as the inter-dot spacing by combining the finite element method and tight-binding method. Regarding the calculated energy band structure, the detailed balance model has been employed and the conversion efficiency has been estimated to be 56.3%.
2 citations
19 May 2011
TL;DR: In this paper, a low angle incidence sputtering (LIA) method was used to obtain an atomically flat Pb(Zr,Ti)O3 substrate for the fabrication of high capacity ferroelectric random access memory devices (FeRAM).
Abstract: The fabrication of ferroelectric nanocrystal materials such as Pb(Zr,Ti)O3 has been widely researched because of the development of high capacity ferroelectric random access memory devices (FeRAM) and ferroelectric domain physics at the nano scale. The ultra flat surface of electrically conductive materials such as Pt is required for the deposition of the ferroelectric nanocrystal substrate. In this paper, Pt deposition was performed using our newly developed sputtering method (low angle incidence sputtering) on an atomically flat sapphire substrate. Due to Volmer-Waber growth, the sputtered Pt grew into island crystals at the normal deposition rate. However, lateral growth of Pt occurred at a very low rate, and the ultra thin atomically flat Pt layer could be obtained on the atomically flat sapphire surface. The Pt thin layer was also evaluated using electrically conductive atomic force microscope (C-AFM) measurement, confirming electric conduction of the atomically flat Pt layer. The obtained atomically flat Pt layer is expected to be utilized for electrical evaluation of PbTiO 3 nanocrystal array.
19 May 2011
TL;DR: In this article, the effect of various types of strain on the electronic band structure and the transport characteristics in graphene was studied, and it was found that the combination of shear and armchair uniaxial deformation is an effective way to open the band gap, meaning the efficient controllability of the electronic current through graphene.
Abstract: We study the effect of the various types of strain on the electronic band structure and the transport characteristics in graphene. It has been found that the combination of shear and armchair uniaxial deformation is an effective way to open the band gap, meaning the efficient controllability of the electronic current through graphene‥
19 May 2011
TL;DR: Theoretical simulations for spin transfer torque in magnetic tunnel junctions (MTJ) using nonequilibrium Green's function method are presented in this paper, where in-plane and out-of-plane components of STT are calculated for MTJ with various oxide thicknesses, and their bias dependence is investigated.
Abstract: Theoretical simulations for the spin-transfer torque (STT) in magnetic tunnel junctions (MTJs) are presented using nonequilibrium Green's function method. In-plane and out-of-plane components of STT are calculated for MTJs with various oxide thicknesses, and their bias dependence is investigated. The validity of the simple analytical models for STT is also discussed.
19 May 2011
TL;DR: In this article, an atomistic transport simulation based on non-equilibrium Green's function and empirical tight-binding methods has been performed for two-dimensional silicon n-i-p devices with a thin strained layer near the source-channel interface.
Abstract: Atomistic transport simulation based on non-equilibrium Green's function and empirical tight-binding methods has been performed for two-dimensional silicon n-i-p devices with a thin strained layer near the source-channel interface. Simulation results show that a compressive strained layer in the source region and a tensile strained layer in the channel region enhance the Zener tunneling current.
19 May 2011
TL;DR: In this article, Ni/Au and Ti/Al/Mo/au were used for Schottky and ohmic contacts, respectively, and a better fitted characteristic was obtained by calculation of thermionic-field emission.
Abstract: n-GaN Schottky barrier diodes were fabricated on a sapphire substrate. Ni/Au and Ti/Al/Mo/Au were used for Schottky and ohmic contacts, respectively. A better fitted characteristic was obtained by calculation of thermionic-field emission. Similar comparison was made for current-voltage characteristics measured at high temperatures up to 523 K. With the increase in the device temperature, better fitting was obtained with a thermionic emission theory.
19 May 2011
TL;DR: In this paper, a single-photon detector is reported, which utilizes scaled-down SOI MOSFET with single-electron sensitivity, and features low dark count and high-speed operation.
Abstract: A unique single-photon detector is reported, which utilizes scaled-down SOI MOSFET with single-electron sensitivity, and features low dark count and high-speed operation. Several issues related to the device structure, quantum efficiency and operation speed are to be addressed.
19 May 2011
TL;DR: In this paper, a new scaling scheme for the XCT-SOI MOSFET was introduced and preliminary results confirm that this is a promising solution for future ultra low-energy LSIs suitable for medical applications.
Abstract: This paper introduces a new scaling scheme for the XCT-SOI MOSFET and preliminary results. They confirm that the XCT-SOI MOSFET is a promising solution for future ‘ultra low-energy’ LSIs suitable for medical applications.
19 May 2011
TL;DR: In this article, the effect of asymmetry of tunneling dielectric film formed on the drain or source electrode on performance of TFT was examined, and the results strongly indicate that the asymmetric of SiN x film formation influences the performance of tFT.
Abstract: We examined the effect of asymmetry of tunneling dielectric film formed on the drain or source electrode on performance of TFT. We fabricated three kinds of TDTFTs and a conventional TFT. For the experiment which clarifies the asymmetry, the tunneling dielectric film was formed on one electrode, and the electrical characteristics were measured by reversing polarity of the electrode. The dielectric film is SiN x (4.07 nm)/Si0 2 (2.67 nm) composite one. Both the on/off ratio and the subthreshold characteristics of the sample where the positive voltage was applied to the electrode with SiN x /Si0 2 film are superior to the reverse condition of the voltage application. Moreover, for the positive voltage application to the electrode, the performance of the TDTFT is also superior to that of conv. TFT. These results strongly indicate that the asymmetry of SiN x film formation influences the performance of TFT.
19 May 2011
TL;DR: In this article, the surface and interface morphology of a thermally grown SiO 2 /4H-SiC(0001) structure was investigated by atomic force microscopy and transmission electron microscopy.
Abstract: We have investigated the surface and interface morphology of a thermally grown SiO 2 /4H-SiC(0001) structure by atomic force microscopy and transmission electron microscopy. It was found that the surface roughness results in thickness fluctuation of thermal SiO 2 due to the pronounced oxidation near the steps. Thus, the localized high elevated electric field near the steps accelerates dielectric degradation and hence results in poor gate oxide reliability.
19 May 2011
TL;DR: It may be possible to integrate a large-scale artificial neural network comparable to the human brain using poly-Si TFTs, and it is verified that the artificial Neural Network can be re-organized by multiple overwriting.
Abstract: Artificial neural networks are promising systems for information processing that have many advantages. Here, we demonstrate an artificial neural network using poly-Si TFTs. It may be possible to integrate a large-scale artificial neural network comparable to the human brain. Particularly in this presentation, we verify that the artificial neural network can be re-organized by multiple overwriting.
19 May 2011
TL;DR: SrBi 4 Ti 4 O 15 (SBTi) and CaBi 4Ti 4O 15 (CBTi) dielectric films of Bismuth-Layered Structure Dielectrics (BLSD) are prepared on Pt film for constructing stacked-type Dielectric capacitors as mentioned in this paper.
Abstract: SrBi 4 Ti 4 O 15 (SBTi) and CaBi 4 Ti 4 O 15 (CBTi) dielectric films of Bismuth Layered Structure Dielectrics (BLSD) are prepared on Pt film for constructing stacked-type dielectric capacitors Compared to perovskite barium titanate family of (Ba,Sr)TiO 3 (BST) case, it is observed that the SBTi film keeps a low leakage of 10−7 A/cm2 at 250 kV/cm and smaller by an order of magnitude than the BST film, even with thinner thickness in the SBTi film This indicates that the SBTi film is effective for applying to high permittivity capacitor with the barium perovskite oxide family
19 May 2011
TL;DR: In this paper, ITO and TiO 2 films were prepared on silicon substrate using spin-coating method and three types of samples were prepared for comparison, they were ITO/TiO 2 (78nm-thick)/Si, ITO or TiO 3 (25nmthick/Si), and ITO /Si.
Abstract: ITO and TiO 2 films were prepared on silicon substrate using spin-coating method. Three types of samples were prepared for comparison. They were ITO/TiO 2 (78nm-thick)/Si, ITO/TiO 2 (25nm-thick)/Si and ITO/Si. The resistivity of an ITO film prepared on TiO 2 was larger than that on Si. Furthermore, the resistivity became larger with increasing the thickness of the underlying TiO 2 layer.
19 May 2011
TL;DR: In this paper, anodic aluminum oxide (AAO) template was formed on Si substrates to control epitaxial crystal growth orientation and diameter of Si nanowires, and the growth direction of nanowire was determined by choosing orientation of Si substrate.
Abstract: Control of epitaxial crystal growth orientation and diameter of Si nanowires were accomplished using anodic aluminum oxide (AAO) template formed on Si substrates. Vapor-Liquid-Solid (VLS) growth of Si nanowires was initiated on the size-controlled Au catalyst electrodeposited in AAO, and growth direction of nanowire was determined by choosing orientation of Si substrate.
19 May 2011
TL;DR: In this article, the fabrication of thin barrier metal layer in a high aspect ratio TSV using electroless plating with Pd nanoparticles (NPs) as a catalyst was investigated.
Abstract: The fabrication of thin barrier metal layer in a high aspect ratio TSV using electroless plating with Pd nanoparticles (NPs) as a catalyst was investigated. We succeeded in the formation of thin continuous electroless barrier metal layer for a high aspect ratio TSV with addition of adequate amount of additives. Adhesion strength of Co-W-B barrier metal increased with decreasing film thickness. The adhesion strength of barrier film increased with annealing at 200 °C, and it was strong enough for practical application.
19 May 2011
TL;DR: In this paper, the carrier conduction in organic thin-film transistor (OTFT) was investigated by using pentacene OTFT with various film thicknesses from 1 to 50nm.
Abstract: Carrier conduction in organic thin-film transistor (OTFT) was investigated by using pentacene OTFT with various film thicknesses from 1 to 50nm. The I on of 3nm OTFT was higher than that of 50nm OTFT. The lateral distance between pentacene molecules decreased with decreasing film thickness. It is considered that the triangle potential was formed at interface between pentacene and SiO 2 in OTFT using very thin pentacene film. Therefore, the probability of the carrier scattering decreases for OTFT with 3nm thickness.
19 May 2011
TL;DR: In this paper, the Hall effect in micro poly-Si Hall devices with p-type doping films was analyzed for magnetic area sensors, and the obtained results suggest the possibility of area sensors using micro polySi Hall device.
Abstract: Hall effect in micro poly-Si Hall devices with p-type doping films is analyzed for magnetic area sensors. Normal Hall voltage (V H ) occurs, and its change is proportional to the magnetic field (B). However, V H has an offset voltage (V O ) even when B = 0, and V H continuously varies even when the polarities of B is reversed whereas the polarities of V H is reversed when the polarities of the control current (I) is reversed. V O originates from zigzag paths of I. The obtained results suggest the possibility of area sensors using micro poly-Si Hall devices.
19 May 2011
TL;DR: In this paper, the effect of the deposition temperature during plasma assisted atomic layer deposition (PA-ALD) on the performance of ZnO TFTs was investigated, and it was shown that improvement of the crystallinity of the TFT films leads to an increase of the on-current.
Abstract: We investigated the effect of the deposition temperature during plasma-assisted atomic layer deposition (PA-ALD) on the performance of ZnO TFTs. The ZnO TFTs with the channel layers deposited at 300°C exhibited high on-current compared with the TFTs with the channel layers deposited at 100°C. X-ray diffraction measurement, the 300°C-ZnO TFTs films have high crystallinity compared with the 100°C-ZnO films. It suggests that improvement of crystallinity of ZnO films leads to the increase of the on-current.
19 May 2011
TL;DR: In this article, fabricated ReRAM using Fe-oxide nano particles (NPs) utilizing bio nano process were produced by ferritin protein and the ReRAM with Feoxide NPs showed stable switching behavior.
Abstract: This study reports fabricated ReRAM using Fe-oxide nano particles (NPs) utilizing bio nano process. Fe-oxide NPs were produced by ferritin protein. The ReRAM with Fe-oxide NPs shows stable switching behavior. This result indicates that the nano particle utilizing BNP can be applied to a nanoscale memory.
19 May 2011
TL;DR: In this article, the thermal stability of ultrathin germanium oxynitride (GeON) gate dielectrics fabricated by plasma nitridation of ultra-thin thermal oxide (GeO 2 ) was investigated.
Abstract: We have investigated the thermal stability of ultrathin germanium oxynitride (GeON) gate dielectrics fabricated by plasma nitridation of ultrathin thermal oxide (GeO 2 ). Thermal treatment up to 520°C effectively improved the electrical properties of the ultrathin GeON dielectrics, such as reduced bulk and interface defects.
19 May 2011
TL;DR: Wang et al. as mentioned in this paper proposed laser direct patterning of Si films by Ag-induced layer exchange, where an Ag film was deposited for middle layer between an a-Si film and a substrate.
Abstract: Direct patterning of Si films is one of promising methods for TFT display fabrication to achieve low cost. We have proposed laser direct patterning of Si films by Ag-induced layer exchange. In this method, an Ag film was deposited for middle layer between an a-Si film and a substrate. Next, pulsed laser was locally irradiated to the Si/Ag film, and the Ag film was segregated to Si film surface. After that, the Ag film at irradiation area and the Ag film of middle layer at non-irradiation area were etched off by nitric acid treatment. In the result, direct patterning of Si thin films can be achieved at laser irradiation area. Moreover, in order to observe segregation behavior of Ag to Si surface, CW laser was coaxially inserted to surface with the pulsed laser, and reflective intensity of the CW laser was measured by Si-photo detector.