Showing papers presented at "International Meeting for Future of Electron Devices, Kansai in 2019"

Enhanced Mobile Robot Localization with Lidar and IMU Sensor

Abstract: Lidar technology is widely used in performing robot localization. However, when only Lidar is being used, the accuracy of localization is not high. In this paper, we present a technique to integrate IMU sensor into a mobile robot equipped with Lidar module. With the heading and direction information (odometer) generated from IMU, the localization error introduced by Lidar can be corrected from time to time. Experimental results show that the robot is able to perform better localization with the introduction of IMU sensor.

Keynote Speech: Information processing hardware, physical reservoir computing and complex-valued neural networks

Abstract: First we discuss the essence of neural networks, which are the bases of modern artificial intelligence (AI), to examine the relationship between the neural fundamental framework and the present hardware. Then, in this context, we review reservoir computing and complex-valued neural networks.

Invited: Solid-State Lithium Thin-Film Batteries Capable of Fast Charging

Abstract: Solid-state Li batteries are promising energy storage devices owing to their high-energy densities with improved safety. However, the large resistance at the interface of solid-electrolytes and electrodes hinders the fast charging and discharge of solid-state Li batteries. Accordingly, understanding electronic and ionic transport properties across interfaces is crucial for designing highperformance solid-state lithium batteries. Here, we introduced the semiconductor technology and their knowledge into battery research. The model solid-electrolyte/electrode interfaces were fabricated using epitaxial thin film growth techniques. We succeeded in demonstrating the interface resistance below 5 Ωcm2 (Li 3 PO 4 /LiCoO 2 interface [1], [2], Li 3 PO 4 /LiNi 0.5 Mn 1.5 O 4 interface [3]); the value is smaller than that of liquid-electrolyte-based Li-ion batteries. Furthermore, we found that the deteriorated interfaces improve by annealing the model interfaces. These studies strongly encourage solid-state Li battery research by demonstrating a very low interface resistance leading to fast charging and discharging.

Invited: Polymer Light-Emitting Devices with Selectively Transparent Photonic Crystals Consisting of Printed Inorganic/Organic Hybrid Dielectric Films

Abstract: Selectively transparent photonic crystals consisting of printed inorganic/organic hybrid dielectric films based on inorganic copper(I) thiocyanate can be produced to exhibit intense Bragg peaks over their stop band in the visible region. This work exhibits a unique approach to achieve the improvement of color purity and the strong directed emission pattern for polymer light-emitting diodes and AC-driven electroluminescent devices with printed inorganic/organic hybrid dielectric mirrors, which will be important for all-printed microlight sources.

Industrial device manufacturing process technologies toward the future: Invited Paper

Abstract: ICT, IoT, 5G, Eco, Mobile society and solution need more and more semiconductors and sensors. We, SPP-Technologies (SPT) have an extensive experience and deep knowledge on the plasma processing for volume production. There are plasma etching including Bosch process, several deposition technologies, thermal processing and other process technologies for industrial device manufacturing.

Invited: Process and Characterization of Vertical Ga 2 O 3 Transistors

Abstract: Gallium oxide $(\mathbf{Ga}_{2}\mathbf{O}_{3})$ is an emerging ultra-wide-bandgap semiconductor especially suitable for high-power and/or high-voltage switching device applications. In this paper, device fabrication process and characteristics of depletion-mode and enhancement-mode vertical $\mathbf{Ga}_{2}\mathbf{O}_{3}$ transistors fabricated by using a multiple ion-implantation doping process are discussed.

Impact of SiN capping during Ohmic Annealing on Performance of GaN-based MISHEMTs

Abstract: We investigated the effect of SiN capping of the AlGaN surface during ohmic annealing process on the performance of AlGaN/GaN HEMTs. In comparison with the devices without any capping, devices with SiN capping exhibited small variation in threshold voltage from sample to sample with smaller hysteresis of transfer curves. It was verified that the SiN cap during ohmic annealing is effective in reducing threshold voltage instabilities in AlGaN/GaN MIS-HEMTs.

Keynote Speech: Nanostructure thermoelectrics

Abstract: Thermoelectric materials reusing waste heat have drawn much attention for overcoming the energy problem. In the development of thermoelectric material, there has been a crucial bottleneck for high thermoelectric conversion efficiency: intercorrelated relationship among the three properties of electrical conductivity, Seebeck coefficient, and thermal conductivity. Many researchers have proposed nanostructuring approaches such as nanocomposite, low- dimensional structure and complex structure, to increase the thermoelectric conversion efficiency. Recently, thin film thermoelectric material is attracting much attention as one- chip stand-alone power source of IoT sensor. Until now, we have studied thin film thermoelectric materials composed of eco-friendly light elements using nanostructures. Here, we present 3 methodologies for realizing high-performance thermoelectric materials. (1) Epitaxial connected Si nanodots exhibited anomalously-low thermal conductivity beating amorphous limit. (2) In Si films including Ge nanodots, thermal conductivity was reduced while maintaining electrical conductivity, demonstrating the independent control of phonon and electron. (3) ZnO nanowire embedded-structure exhibited higher thermoelectric power factor than that of conventional ZnO films. The thermoelectric power factor enhancement was brought by Seebeck coefficient enhancement due to smooth transport of higher energy carrier than energy barrier height through the nanowires/films interfaces. These successes largely accelerate the development of thermoelectric materials.

Microstructures of $\varepsilon - \mathrm{Ga}_{2}\mathrm{O}_{3}$ thin film on (100) TiO 2 substrate by mist chemical vapor deposition

Abstract: Orthorhombic $\varepsilon-\mathrm{Ga}2\mathrm{O}_{3}$ film was grown on (100) TiO 2 substrate by mist CVD. XRD and TEM revealed that the thin film was a two-layer structure of $\varepsilon - \mathrm{Ga}2\mathrm{O}_{3}$ and $\beta-$ Ga2O 3 layers. Epitaxial orientation relationships were identified as (001) $\varepsilon - \mathrm{Ga}_{2}\mathrm{O}_{3} [010]\Vert (1-30)\beta-\mathrm{Ga}_{2}\mathrm{O}_{3}[132]\Vert$ (100) TiO 2 [001] by SAED analysis.

Sub-gap defect states in back-channel-etched amorphous In-Ga-Zn-O TFTs studied by photoinduced transient spectroscopy

Abstract: We have studied changes of sub-gap defect states in amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) by means of photoinduced transient spectroscopy (PITS). It is found that the sub-gap states in the channel region of a-IGZO TFTs were drastically modified as back-channel etch process proceeded. The change was due to in-and out-diffusion of hydrogen atoms in the channel region of a-IGZO TFTs, which affects the performance of the a-IGZO TFTs.

The Recent Resolution and Detection Limit Improvement of EDS and EBSD with SEM: Invited Paper

Abstract: EDS and EBSD analysis have been developed more than half a century. As of the X-ray and electron detection devices and software is improved much, the detection limit is also improved now.

High reliability InGaZnO TFT by inductively coupled plasma sputtering system

Abstract: The reliability of oxide semiconductor TFT and the method to lower the process temperature have become serious problems. In order to solve these problems we have developed inductively coupled plasma sputtering equipment that can control the Radio Frequency (RF) power to generate Inductively Coupled Plasma (ICP) and the voltage applied to the sputtering target independently. Using this equipment, we can deposit high-density oxide semiconductor films at room temperature and fabricate highly reliable TFTs with them.