The Japanese Journal of Applied Physics (JJAP) is an international journal for the advancement and dissemination of knowledge in all fields of applied physics. The journal publishes articles dealing with the applications of physical principles as well as articles concerning the understanding of physics that have particular applications in mind. It is published by IOP Publishing Ltd on behalf of the Japan Society of Applied Physics (JSAP).
This publication is partially supported by a Grant-in-Aid for Publication of Scientific Research Results from the Japan Society for the Promotion of Science.
Congratulations to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura on being awarded the 2014 Nobel Prize for Physics. Several of the key papers cited by the Nobel committee were published in this journal - visit the 2014 Nobel collection to read them for free.
From 2014, JJAP will be published by IOP Publishing on behalf of The Japan Society of Applied Physics. All submissions and refereeing will continue to be handled by the JJAP Editorial Office at The Japan Society of Applied Physics. To submit a paper to JJAP, please connect to the editorial website.
JJAP publishes a number of Special Issues each year. These feature research articles presented at major international conferences. These articles are fully peer-reviewed to JJAP's usual acceptance criteria. Fifteen special issues are planned for 2014. Click here for a list of the 2014 Special Issues.
In the last 30 days
Shintaro Sato 2015 Jpn. J. Appl. Phys. 54 040102
Graphene is a two-dimensional material with a one-atom-thick layer of carbon. Since the first report of the excellent electrical properties of graphene in 2004, its unique physical properties have been attracting attention and research on the application of graphene to electronic and photonic devices has been intensively carried out. In this review, recent research trends in the application of graphene to electronic devices, particularly transistors and interconnects, and graphene formation techniques are examined. In addition, the technical issues to be addressed for its application to electronic devices and the prospects for future graphene devices are discussed.
Tsunenobu Kimoto 2015 Jpn. J. Appl. Phys. 54 040103
Power semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600–1700 V) SiC Schottky barrier diodes (SBDs) and power metal–oxide–semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.
Takashi Suemasu 2015 Jpn. J. Appl. Phys. 54 07JA01
Semiconducting BaSi 2 has attractive features for thin-film solar cell applications because both a large absorption coefficient and a long minority-carrier diffusion length can be utilized. In this article, we explore the possibility of semiconducting BaSi 2 films for thin-film solar cell applications. Recent experimental results on the optical absorption coefficient, minority-carrier diffusion length, and minority-carrier lifetime in undoped n-BaSi 2 films are presented. After that, the photoresponse spectra are calculated for a BaSi 2 p +n abrupt homojunction diode based on the one-dimensional carrier continuity equation using previously reported experimental values. The individual contributions of the three layers, that is, the neutral p +-type layer, the depletion region, and the neutral n-type layer, to the total photoresponse are discussed. The photoresponse depends on parameters such as layer thickness, minority-carrier diffusion length, and surface recombination velocity. We further estimate the photocurrent density and the open-circuit voltage under AM 1.5 illumination.
Hiroshi Amano et al 1989 Jpn. J. Appl. Phys. 28 L2112
Distinct p-type conduction is realized with Mg-doped GaN by the low-energy electron-beam irradiation (LEEBI) treatment, and the properties of the GaN p-n junction LED are reported for the first time. It was found that the LEEBI treatment drastically lowers the resistivity and remarkably enhances the PL efficiency of MOVPE-grown Mg-doped GaN. The Hall effect measurement of this Mg-doped GaN treated with LEEBI at room temperature showed that the hole concentration is ∼2·10 16cm -3, the hole mobility is ∼8 cm 2/V·s and the resistivity is ∼35 Ω·cm. The p-n junction LED using Mg-doped GaN treated with LEEBI as the p-type material showed strong near-band-edge emission due to the hole injection from the p-layer to the n-layer at room temperature.
Tatau Nishinaga 2015 Jpn. J. Appl. Phys. 54 050101
The impacts of the progress in the art and science of crystal growth on human life are reviewed. Even before the invention of the transistor, quartz and corundum crystals were used as crystal oscillators and jewel bearings, respectively. However, a major impact of crystal growth on society was experienced with the invention of the transistor, which required high-purity and perfect germanium crystals. Once the importance of crystal growth was clearly recognized, the science of crystal growth also extensively developed. The growth of single crystalline silicon allows us to produce integrated circuits, which are used in all the electronic devices in everyday use. The technological developments in the growth of compound semiconductors have also had a large impact on society through the inventions of the laser diode for optical communication and the p–n junction nitride light-emitting diode toward the realization of a less energy-intensive society. The latter invention was awarded the 2014 Nobel Prize in Physics. Finally, future aspects of crystal growth are discussed.
Kazuhito Hashimoto et al 2005 Jpn. J. Appl. Phys. 44 8269
Photocatalysis has recently become a common word and various products using photocatalytic functions have been commercialized. Among many candidates for photocatalysts, TiO 2 is almost the only material suitable for industrial use at present and also probably in the future. This is because TiO 2 has the most efficient photoactivity, the highest stability and the lowest cost. More significantly, it has been used as a white pigment from ancient times, and thus, its safety to humans and the environment is guaranteed by history. There are two types of photochemical reaction proceeding on a TiO 2 surface when irradiated with ultraviolet light. One includes the photo-induced redox reactions of adsorbed substances, and the other is the photo-induced hydrophilic conversion of TiO 2 itself. The former type has been known since the early part of the 20th century, but the latter was found only at the end of the century. The combination of these two functions has opened up various novel applications of TiO 2, particularly in the field of building materials. Here, we review the progress of the scientific research on TiO 2 photocatalysis as well as its industrial applications, and describe future prospects of this field mainly based on the present authors' work.
Shuji Nakamura 1991 Jpn. J. Appl. Phys. 30 L1705
High-quality gallium nitride (GaN) film was obtained for the first time using a GaN buffer layer on a sapphire substrate. An optically flat and smooth surface was obtained over a two-inch sapphire substrate. Hall measurement was performed on GaN films grown with a GaN buffer layer as a function of the thickness of the GaN buffer layer. For the GaN film grown with a 200 Å-GaN buffer layer, the carrier concentration and Hall mobility were 4×10 16/cm 3 and 600 cm 2/V·s, respectively, at room temperature. The values became 8×10 15/cm 3 and 1500 cm 2/V·s at 77 K, respectively. These values of Hall mobility are the highest ever reported for GaN films. The Hall measurement shows that the optimum thickness of the GaN buffer layer is around 200 Å.
Chihaya Adachi 2014 Jpn. J. Appl. Phys. 53 060101
Currently, organic light-emitting diodes (OLEDs) have reached the stage of commercialization, and there are intense efforts to use them in various applications from small- and medium-sized mobile devices to illumination equipment and large TV screens. In particular, phosphorescent materials have become core OLED materials as alternatives to the conventionally used fluorescent materials because devices made with phosphorescent materials exhibit excellent light-emitting performance. However, phosphorescent materials have several problems, such as their structure being limited to organic metal compounds containing rare metals, for example, Ir, Pt, and Os, and difficulty in realizing stable blue light emission, so the development of new materials is necessary. In this article, I will review next-generation OLEDs using a new light-emitting mechanism called thermally activated delayed fluorescence (TADF). Highly efficient TADF, which was difficult to realize with conventional technologies, has been achieved by optimizing molecular structures. This has led to the realization of ultimate next-generation OLEDs that are made of common organic compounds and can convert electricity to light at an internal quantum efficiency of nearly 100%.
Tomohito Sekine et al 2015 Jpn. J. Appl. Phys. 54 04DK10
We report on the high mechanical stability of flexible printed organic thin-film transistor (OTFT) devices under high bending stress conditions. The mechanical stability of organic TFT devices using a semiconducting polymer, PBTTT-C16, was comparable to that of OTFT devices using a typical small-molecule semiconductor, pentacene. The drain current of small-molecule OTFT devices decreased by nearly 60% at a 1.5% tensile strain in a direction parallel to the transistor channel, whereas that of polymer-based OTFT devices decreased by only 10% at the same tensile strain. Furthermore, polymer-based OTFT devices exhibited no significant changes in their electrical characteristics after 1000 bending cycles. This stability could be attributed to the high density and good uniformity of the semiconducting polymer layer. Our results indicate that the OTFT devices with polymer-based semiconducting materials have excellent operational stability and reliability under severe bending stress conditions.
Shizuo Fujita 2015 Jpn. J. Appl. Phys. 54 030101
Wide-bandgap semiconductors are expected to be applied to solid-state lighting and power devices, supporting a future energy-saving society. While GaN-based white LEDs have rapidly become widespread in the lighting industry, SiC- and GaN-based power devices have not yet achieved their popular use, like GaN-based white LEDs for lighting, despite having reached the practical phase. What are the issues to be addressed for such power devices? In addition, other wide-bandgap semiconductors such as diamond and oxides are attracting focusing interest due to their promising functions especially for power-device applications. There, however, should be many unknown phenomena and problems in their defect, surface, and interface properties, which must be addressed to fully exploit their functions. In this review, issues of wide-bandgap semiconductors to be addressed in their basic properties are examined toward their “full bloom”.