Showing papers presented at "International Meeting for Future of Electron Devices, Kansai in 2018"
01 Jun 2018
TL;DR: In this article, a p+-Si/patterned Al was successfully fabricated in alignment to SiO 2 /p+ -Si junction by surface-activated bonding (SAB) of a p +-Si substrate and a patterned Al layer, which showed the superiority of using patterned metal layer to directly-bonded semiconductor.
Abstract: We successfully fabricate a p+-Si//patterned Al in alignment to SiO 2 /p+ -Si junction by surface-activated bonding (SAB) of a p+-Si substrate and a patterned Al layer. We find that the interface resistance, which is 0.025 Ω.cm2 in a junction annealed at 300 °C, is much lower than p+ -Si/p+ -Si junction by SAB. This result shows the superiority of junctions using patterned metal layer to directly-bonded semiconductor.
7 citations
01 Jun 2018
TL;DR: In this paper, Corundum-structured Ga203 is a new candidate for next-generation power device materials due to its excellent physical properties, and thin film SBDs with extremely low specific on-resistance of 0.1 m Ωcm2 (breakdown voltage 531 V) were successfully fabricated using MIST EPITAXY® technology.
Abstract: Corundum-structured Ga203 is a new candidate for next-generation power device materials due to its excellent physical properties. Thin film SBDs with extremely low specific on-resistance of 0.1 m Ωcm2(breakdown voltage 531 V) were successfully fabricated using MIST EPITAXY® technology.
4 citations
21 Jun 2018
TL;DR: A new physical unclonable function using energy harvesting to prevent semiconductor counterfeits is proposed using dispersion of the power generation time due to product variation of semiconductors.
Abstract: This study proposes a new physical unclonable function using energy harvesting to prevent semiconductor counterfeits. The proposed method uses dispersion of the power generation time due to product variation of semiconductors. Experiments using 5 solar cells evaluate the validity of the proposed method.
4 citations
21 Jun 2018
TL;DR: A special structure of an AIGaN/GaN HEMT is studied, in which an isolated p-GaN layer is located in the gate-drain access region, which resulted in significant suppression in current collapse by 98 % as compared to the conventional H EMT.
Abstract: For the purpose of reducing current collapse, we have studied a special structure of an AIGaN/GaN HEMT, in which an isolated p-GaN layer is located in the gate-drain access region. An addition of an isolated p-GaN layer resulted in significant suppression in current collapse by 98 %, as compared to the conventional HEMT. It was also found that current collapse was more effectively suppressed when the p-GaN region was located closer to the gate.
3 citations
01 Jun 2018
TL;DR: This study proposes the small scale countermeasure against power analysis attacks for a lightweight block cipher, which can be implemented on small scale devices.
Abstract: A lightweight block cipher which can be implemented on small scale devices has attracted attention. Regarding tamper resistance, the risk of power analysis attacks has been reported even though the encryption algorithm is computationally secured. Therefore, countermeasures for power analysis attacks are very important. This study proposes the small scale countermeasure against power analysis attacks for a lightweight block cipher.
2 citations
01 Jun 2018
TL;DR: In this paper, the gate-to-drain capacitance (Miller capacitance) of lateral tunnel FETs is discussed and how to reduce the mirror capacitance of LTFETs.
Abstract: This paper discusses aspects of gate-to-drain capacitance (Miller capacitance) of lateral tunnel FETs (LTFETs). It is considered how to reduce the mirror capacitance of LTFET.
2 citations
01 Jun 2018
TL;DR: In this paper, a wet etching has been performed using an electrochemical etching method to fabricate mesa-structure vertical GaN p-n junction diodes.
Abstract: A wet etching has been performed using an electrochemical etching method to fabricate mesa-structure vertical GaN p-n junction diodes. In case of conventional dry etching, the breakdown voltages of the p-n diodes showed scattered values probably due to local concentration of electric field by roughness at the side wall of the mesa. Smooth and damage-free surface have been obtained by the wet etching, which has enabled higher and stable the breakdown voltages.
2 citations
21 Jun 2018
TL;DR: In this paper, a dual-field-plate (FP) was used to suppress the current collapse in AlGaN/GaN MOS-HEMTs with a pulsed I-V technique.
Abstract: We fabricated AlGaN/GaN MOS-HEMTs with a dual-field-plate (FP), composed of gate-FP and source-FP. Using pulsed I-V technique, the effect of FP on current collapse was studied. Applying a high positive gate voltage resulted in current collapse suppression. It was found that the use of dual-FP was effective to significantly suppress the current collapse.
2 citations
21 Jun 2018
TL;DR: In this article, a novel structure for a vertical power MOSFET is designed to have higher breakdown voltage and lower specific on-state resistance compared with a conventional VPPM.
Abstract: In this paper, a novel structure for a vertical power MOSFET is designed to have higher breakdown voltage and lower specific on-state resistance compared with a conventional vertical power MOSFET.
2 citations
21 Jun 2018
TL;DR: In this paper, the breakdown electric field and resistivity of Fe-doped semi-insulating GaN substrates with various Fe doping concentrations were studied and it was found that increasing the Fe concentration was effective to enhance the resistivity and effective lateral breakdown electric fields.
Abstract: In this work, we study the breakdown electric field and resistivity of Fe-doped semi-insulating GaN substrates with various Fe doping concentrations. The substrate with Fe doping concentration of 4×1020 cm−3 exhibited an effective lateral breakdown field of 2 MV/cm with a resistivity of more than 1012Ωcm. It was found that increasing the Fe concentration was effective to enhance the resistivity and effective lateral breakdown electric field.
1 citations
01 Jun 2018
TL;DR: An amorphous oxide semiconductors (AOSs) In-Ga-Zn-O(IGZO) thin film for a memristor characteristic device was proposed in this article.
Abstract: In this presentation, we propose an amorphous oxide semiconductors (AOSs) In-Ga-Zn-O(IGZO) thin film for a memristor characteristic device. We fabricated the memristor characteristic device active layer using IGZO and electrodes using aluminum by physical vapor deposition (PVD). The AI/IGZO/ Al cell device showed the bipolar switching characteristic of a switching voltage 2 and reproducibility 10.
21 Jun 2018
TL;DR: This work focused on the nonlinearity of spin dynamics and formed a virtual artificial neural network by using the time multiplexing method and succeeded in speech recognition with a high recognition rate of 99.6%.
Abstract: Neural networks and artificial intelligence utilizing artificial neurons and synapses are attracting much attention. Spintronic devices are considered to be suitable for mimicking artificial synapses and artificial neurons because of nonvolatility of information and rich nonlinearity of spin dynamics. We focused on the nonlinearity of spin dynamics and formed a virtual artificial neural network by using the time multiplexing method. By using reservoir computing for learning rules, we succeeded in speech recognition with a high recognition rate of 99.6%. These results pave the way for hardware implementation of artificial intelligence.
21 Jun 2018
TL;DR: In this article, the authors studied hysteresis in transfer characteristics of GaN-based vertical trench MOSFETs fabricated using different process technologies for n+ -GaN source layer.
Abstract: In this paper, we studied hysteresis in transfer characteristics of GaN-based vertical trench MOSFETs fabricated using different process technologies for n+ -GaN source layer. It was found that the device with epitaxially-grown source region can suppress hysteresis in the transfer characteristics compared to that with implanted source region.
21 Jun 2018
TL;DR: In this paper, the MBE growth of WO 3 on (100) LSAT substrates is reported and it is revealed that the initial layer crystallizes in the cubic WO3 structure although the lattice constant in the growth direction is shrunken due to the coherent growth.
Abstract: MBE growth of WO 3 on (100) LSAT substrates is reported. It is revealed that the initial WO 3 layer crystallizes in the cubic WO 3 structure although the lattice constant in the growth direction is shrunken due to the coherent growth. This cubic structure is relaxed and becomes close to the orthorhombic WO 3 structure with increasing thickness. The electron mobility in a 5 nm thick film was as large as 560 cm2/Vs while it decreased to the typical vale of bulk crystals of about 10 cm2/Vs in the thicker films more than 30 nm.
21 Jun 2018
TL;DR: A multilayer cross-point device using In-Ga-Zn-O semiconductor for synapse elements that gradually degrades by flowing current is developed and is available for modified Hebban learning.
Abstract: We have developed a multilayer cross-point device using In-Ga-Zn-O semiconductor for synapse elements. There are 200 synapses on a glass substrates. We evaluate the change in the current value of the synapse. The current value gradually degrades by flowing current. The characteristic is available for modified Hebban learning.
01 Jun 2018
TL;DR: In this paper, a thermal hybrid solar cell system was investigated using Si solar cells and concentrating optical system of a linear Fresnel lens and a parabolic mirror, which was improved by additional mirrors and thermal insulators on the solar cells.
Abstract: A thermal hybrid solar cell system is investigated using Si solar cells and concentrating optical system of a linear Fresnel lens and a parabolic mirror. Total energy usage efficiency is improved by additional mirrors and thermal insulators on the solar cells.
01 Jun 2018
TL;DR: In this article, the low-frequency effect showing abrupt change of intrinsic output capacitance and conductance for high resistivity PD-SOI MOSFETs is well modeled using an improved RF output equivalent circuit with a series RC network.
Abstract: The low-frequency effect showing abrupt change of intrinsic output capacitance and conductance for high resistivity(HR) PD-SOI MOSFETs is well modeled using an improved RF output equivalent circuit with a series RC network. The output circuit parameters are accurately extracted by fitting frequency-dependent output capacitance and conductance equations to each measured data. The good agreements between measured and modeled Y 22 -parameter are obtained from 50 MHz to 10GHz.
01 Jun 2018
TL;DR: In this article, the authors studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf, Hf02/Au ReRAM device and suggested that the optimum thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current.
Abstract: Resistive random access memory (ReRAM) devices with a Hf02 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/Hf02/Au ReRAM device. It is suggested that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current.
21 Jun 2018
TL;DR: In this article, the authors measured electrical characteristics and die shear strength of directly-bonded n-4H-SiC/p+-Si junction with emphasis on their dependence on the annealing condition during bonding.
Abstract: We measure electrical characteristics and die shear strength of directly-bonded n-4H-SiC/p+-Si junction with emphasis on their dependence on the annealing condition during bonding. In the bonding process, we perform lower-temperature annealing at the first step and higher-temperature one at the second step. By increasing annealing temperature at the first step, the impurity concentration obtained by C-V measurement gets close to the impurity concentration of SiC and the bonding strength become larger. These results show that directly-bonded SiC/Si junction characteristics depend on the annealing temperature at the first (lower-temperature) step in the bonding process.
01 Jun 2018
TL;DR: This work has developed multilayer cross-point synapses using Ga-Sn-O (GTO) thin films for neural networks that can be applied to the modified Hebb's learning rule.
Abstract: We have developed multilayer cross-point synapses using Ga-Sn-O (GTO) thin films for neural networks. Twenty intermediate layer metal lines and ten lower and upper layer metal lines make 400 cross-point synapses integrated on a glass substrate. By continuously applying a constant voltage to the GTO thin films, the current value is changed. As a result, we obtained degradation that can be applied to the modified Hebb's learning rule.
21 Jun 2018
TL;DR: In this paper, a Ga-Sn-O (GTO) film for a thin-film transistor (TFT) using mist chemical vapor deposition (CVD) was constructed.
Abstract: We have succeeded in forming a Ga-Sn-O (GTO) film for a thin-film transistor (TFT) using mist chemical vapor deposition (CVD). The field effect mobility is 0.30 cm2. V−1. S−1 and the threshold voltage is 12.7 V. This result suggests a possibility of rare-metal free amorphous metal-oxide semiconductors.
01 Jun 2018
TL;DR: In this paper, the Schottky barrier diodes that are fabricated on wet-etched surfaces after irradiation of Ar fast atom beams (F AB) were examined.
Abstract: Characteristics of damages in n-Si due to irradiation of Ar fast atom beams (F AB) are examined. Their penetration depth is estimated to be ≈ 50 nm by analyzing current-voltage characteristics of n-Si Schottky barrier diodes that are fabricated on wet-etched surfaces after irradiation of Ar F AB.
21 Jun 2018
TL;DR: In this paper, a Ga-Sn-O (GTO) film for a thin film transistor (TFT) was constructed by using a RF magnetron sputtering at room temperature and applying UV annealing (254 nm) treatment.
Abstract: We succeeded in forming a Ga-Sn-O (GTO) film for a thin film transistor (TFT) by using a RF magnetron sputtering at room temperature and applying UV annealing (254 nm) treatment. The field effect mobility is 3.53 cm2/V · S. This result suggests the possibility of a rare metal free amorphous metal oxide semiconductor.
01 Jun 2018
TL;DR: In this paper, a GTO thin film thermoelectric conversion devise by the mist CVD method was proposed, which had a Seebeck coefficient of −193[µV/K], a conductivity of 6.35[S/cm], and a PF of 0.0179 [mW/mK2].
Abstract: We proposed a GTO thin film thermoelectric conversion devise by the mist CVD method. The thermoelectric conversion devise with the best performance had a Seebeck coefficient of −193[µV/K], a conductivity of 6.35[S/cm], and a PF of 0.0179 [mW/mK2].
21 Jun 2018
TL;DR: In this article, the authors evaluated (Bi, La) 4 Ti 3 O 12 (BLT) thin films for capacitor-type synapses and found that the larger the film thickness of the ferroelectric thin film, the more useful it is as synapses.
Abstract: We evaluated (Bi, La) 4 Ti 3 O 12 (BLT) thin films for capacitor-type synapses. The ferroelectric thin films were formed by a sol-gel method. The hysteresis characteristics of the ferroelectric thin films were evaluated using a Sawyer-Tower-Circuit. The results show that the larger the film thickness of the ferroelectric thin film, the more useful it is as synapses.
21 Jun 2018
TL;DR: Aiming towards fail-safe normally-off operation, the authors in this paper have fabricated AlGaN/GaN HEMTs with p-GaN gate and have confirmed that threshold voltage was shifted towards the positive direction with increasing pGaN layer thickness and this amount of shift was further enhanced by post-gate deposition annealing.
Abstract: Aiming towards fail-safe normally-off operation we have fabricated AlGaN/GaN HEMTs with p-GaN gate. From device transfer characteristics, we have confirmed that threshold voltage (Vth) was shifted towards the positive direction with increasing p-GaN layer thickness and this amount of shift was further enhanced by post-gate deposition annealing.
21 Jun 2018
TL;DR: In this paper, a highly sensitive transient photocapacitance measurement system for deep defects in wide bandgap materials, and applied it to characterize the boron-doped diamond films grown on a high-pressure/high-temperature-synthesized Ib diamond substrate using high power-density microwave-plasma chemical vapor deposition method.
Abstract: We have developed a highly-sensitive transient photocapacitance measurement system for deep defects in wide bandgap materials, and applied it to characterize the boron-doped diamond films grown on a high-pressure/high-temperature-synthesized Ib diamond substrate using high-power-density microwave-plasma chemical vapor deposition method. The developed transient photocapacitance measurement system has both a low detection limit of less than 0.5 fF for changes in the photocapacitance and a low measurement temperature drift of less than 0.03 K in 12 h. By using the transient photocapacitance measurement system, we have successfully found an acceptor-type defect around 1.2 eV above the valence band maximum for the B-doped diamond film.
21 Jun 2018
TL;DR: Variations among HRV indices obtained from PWs simultaneously measured at four different sites are examined and those assessed from R-R intervals of electrocardiogram (ECG) are compared.
Abstract: Although pulse wave (PW) is widely used for assessing heart rate variability (HRV) with wearable devices, the variations intrinsically existing in HRV assessment by this method are unknown. This study examined variations among HRV indices obtained from PWs simultaneously measured at four different sites (right and left wrists and forearms) and compared them with those assessed from R-R intervals of electrocardiogram (ECG). While mean interbeat intervals showed good consistency with small inter-site variation (coefficient of variation [CV], 0.8% and 0.5% for supine and sitting positions) and modest deviation from that assessed from ECG (coefficient of deviation [CD], 3.1 % and 2.0%), low and high frequency components of HRV showed non-negligible inconsistency with large inter-site variations (CV, 4.0% and 3.8% for supine and 3.6% and 4.7% for sitting) and deviations from those with ECG (CD, 29.3% and 51.3% for supine and 18.5% and 40.2% for sitting).
01 Jun 2018
TL;DR: In this paper, the authors used scanning capacitance microscopy (SCM) to measure the capacitance transient due to inversion layer formation in a SiO 2 /Si structure.
Abstract: Microscopic characterization of generation lifetimes in a SiO 2 /Si structure has been carried out using scanning capacitance microscopy (SCM). Generation lifetimes could be investigated by monitoring the capacitance transient due to inversion layer formation. The validity of local capacitance transient measurements by SCM was verified by comparing with the results of conventional capacitance transient measurements using a MOS capacitor. Furthermore, it was demonstrated that SCM can be used for imaging of the formation process of the inversion layer on a nanometer scale.
01 Jun 2018
TL;DR: In this article, a comprehensive summary of classification, feature, preparation and preparation of ferroelectric thin films are explained. And electron devices using ferro-electric thin film such as nonvolatile memories FeRAM and FeFET, ultrasonic sensor, infrared sensor and energy harvester are introduced.
Abstract: Comprehensive summary of classification, feature, preparation of ferroelectric thin films are explained. Electron devices using ferroelectric thin films such as nonvolatile memories FeRAM and FeFET, ultrasonic sensor, infrared sensor and energy harvester are introduced. Recent topics on ferroelectric thin films and their electron devices are also added