Search

Full list of authors: Kawauchi, K.; Murgas, F.; Palle, E.; Narita, N.; Fukui, A.; Hirano, T.; Parviainen, H.; Ishikawa, H. T.; Watanabe, N.; Esparaza-Borges, E.; Kuzuhara, M.; Orell-Miquel, J.; Krishnamurthy, V; Mori, M.; Kagetani, T.; Zou, Y.; Isogai, K.; Livingston, J. H.; Howell, S. B.; Crouzet, N.; de Leon, J. P.; Kimura, T.; Kodama, T.; Korth, J.; Kurita, S.; Laza-Ramos, A.; Luque, R.; Madrigal-Aguado, A.; Miyakawa, K.; Morello, G.; Nishiumi, T.; Rodriguez, G. E. F.; Sanchez-Benavente, M.; Stangret, M.; Teng, H.; Terada, Y.; Gnilka, C. L.; Guerrero, N.; Harakawa, H.; Hodapp, K.; Hori, Y.; Ikoma, M.; Jacobson, S.; Konishi, M.; Kotani, T.; Kudo, T.; Kurokowa, T.; Kusakabe, N.; Nishikawa, J.; Omiya, M.; Serizawa, T.; Tamura, M.; Ueda, A.; Vievard, S.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. The NASA space telescope TESS is currently in the extended mission of its all-sky search for new transiting planets. Of the thousands of candidates that TESS is expected to deliver, transiting planets orbiting nearby M dwarfs are particularly interesting targets since they provide a great opportunity to characterize their atmospheres by transmission spectroscopy. Aims. We aim to validate and characterize the new sub-Neptune-sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (d = 33.36 ± 0.02pc, Teff = 3373 ± 108 K) with an orbital period of 7.852 days. Methods. We use TESS data, ground-based multicolor photometry, and radial velocity measurements with the InfraRed Doppler (IRD) instrument on the Subaru Telescope to validate the planetary nature of TOI-2136.01, and estimate the stellar and planetary parameters. We also conduct high-resolution transmission spectroscopy to search for helium in its atmosphere. Results. We confirm that TOI-2136.01 (now named TOI-2136b) is a bona fide planet with a planetary radius of Rp = 2.20 ± 0.07R⊕ and a mass of Mp = 4.7−2.6+3.1 M⊕. We also search for helium 10830 Å absorption lines and place an upper limit on the equivalent width of, The MEarth Project acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering, the National Science Foundation under grants AST-0807690, AST-1109468, AST-1616624 and AST-1004488 (Alan T. Waterman Award), the National Aeronautics and Space Administration under Grant No. 80NSSC18K0476 issued through the XRP Program, and the John Templeton Foundation. Based on observations obtained with the Samuel Oschin 48-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. Z.T.F. is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. Our data reductions benefited from PyRAF and PyFITS that are the products of the Space Telescope Science Institute, which is operated by AURA for NASA. G.M. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 895525. R.L. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación, through project PID2019-109522GB-C52, and the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). J.K. gratefully acknowledge the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). This work is partly supported by JSPS KAKENHI Grant Numbers JP21K20376, JP21K13975, JP21H00035, JP21K20388, JP20K14518, JP20K14521, JP19K14783, JP18H05439, JP17H04574, by Grant-in-Aid for JSPS Fellows Grant Number JP20J21872, by JST CREST Grant Number JPMJCR1761, by Astrobiology Center PROJECT Research AB031014, by Astrobiology Center SATELLITE Research project AB022006, and the Astrobiology Center of National Institutes of Natural Sciences (NINS) (Grant Number AB031010). M.T. is supported by MEXT/JSPS KAKENHI grant Nos. 18H05442, 15H02063, and 22000005. Some of the observations in the paper made use of the High-Resolution Imaging instrument Alopeke obtained under Gemini LLP Proposal Number: GN/S-2021A-LP-105. Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Alopeke was mounted on the Gemini North (and/or South) telescope of the international Gemini Observatory, a program of NSF’s OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation, on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Mnisterio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea).

We analysed 68 candidate planetary systems first identified during Campaigns 5 and 6 (C5 and C6) of the NASA \textit{K2} mission. We set out to validate these systems by using a suite of follow-up observations, including adaptive optics, speckle imaging, and reconnaissance spectroscopy. The overlap between C5 with C16 and C18, and C6 with C17, yields lightcurves with long baselines that allow us to measure the transit ephemeris very precisely, revisit single transit candidates identified in earlier campaigns, and search for additional transiting planets with longer periods not detectable in previous works. Using \texttt{vespa}, we compute false positive probabilities of less than 1\% for 37 candidates orbiting 29 unique host stars and hence statistically validate them as planets. These planets have a typical size of $2.2R_{\oplus}$ and orbital periods between 1.99 and 52.71 days. We highlight interesting systems including a sub-Neptune with the longest period detected by \textit{K2}, sub-Saturns around F stars, several multi-planetary systems in a variety of architectures. These results show that a wealth of planetary systems still remains in the \textit{K2} data, some of which can be validated using minimal follow-up observations and taking advantage of analyses presented in previous catalogs., 25 pages, 12 figures, accepted for publication in MNRAS

The KESPRINT consortium identified K2-216 as a planetary candidate host star in the K2 space mission Campaign 8 field with a transiting super-Earth. The planet has recently been validated as well. Our aim was to confirm the detection and derive the main physical characteristics of K2-216b, including the mass. We performed a series of follow-up observations: high resolution imaging with the FastCam camera at the TCS, the Infrared Camera and Spectrograph at Subaru, and high resolution spectroscopy with HARPS (ESO, La Silla), HARPS-N (TNG), and FIES (NOT). The stellar spectra were analyzed with the SpecMatch-Emp and SME codes to derive the stellar fundamental properties. We analyzed the K2 light curve with the Pyaneti software. The radial-velocity measurements were modelled with both a Gaussian process (GP) regression and the floating chunk offset (FCO) technique to simultaneously model the planetary signal and correlated noise associated with stellar activity. Imaging confirms that K2-216 is a single star. Our analysis discloses that the star is a moderately active K5V star of mass 0.70+/-0.03 Msun and radius 0.72+/-0.03 Rsun. Planet b is found to have a radius of 1.75+0.17-0.10 Rearth and a 2.17-day orbit in agreement with previous results. We find consistent results for the planet mass from both models: 7.4+/-2.2 Mearth from the GP regression, and 8.0+/-1.6 Mearth from the FCO technique, which implies that this planet is a super-Earth. The planet parameters put planet b in the middle of, or just below, the gap of the radius distribution of small planets. The density is consistent with a rocky composition of primarily iron and magnesium silicate. In agreement with theoretical predictions, we find that the planet is a remnant core, stripped of its atmosphere, and is one of the largest planets found that has lost its atmosphere., Comment: 17 pages, 10 figures, accepted by Astronomy & Astrophysics 28 June 2018

The present study has been conducted to clarify the magnetic control characteristics of a particle-laden compressible plasma jet impinging on a substrate for the improvement of a low-pressure plasma spraying process and its controllable optimization. The plasma jet is described by an Eulerian approach and each injected particle is described by a Lagrangian approach, respectively, taking into account the compressible effect, variable transport properties, and plasma–particle interactions, coupled with the Maxwell's equations. The effects of the location of an applied rf electromagnetic field and of the injected particle size on the plasma jet characteristics and the particle behavior are clarified by numerical simulation. It is concluded that the particle dispersion is effectively influenced and, furthermore, the plasma temperature and the particle temperature can be strongly controlled by applying the rf electromagnetic field to the nozzle. The reasonable agreement of particle velocity between calculation and experiment is obtained.

We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation of 55 +/- 2 AU (1.058 +/- 0.007 arcsec) from the B9-type star Kappa And. The planet was detected with Subaru/HiCIAO during the SEEDS survey, and confirmed as a bound companion via common proper motion measurements. Observed near-infrared magnitudes of J = 16.3 +/- 0.3, H = 15.2 +/- 0.2, Ks = 14.6 +/- 0.4, and L' = 13.12 +/- 0.09 indicate a temperature of ~1700 K. The galactic kinematics of the host star are consistent with membership in the Columba association, implying a corresponding age of 30 +20 -10 Myr. The system age, combined with the companion photometry, points to a model-dependent companion mass ~12.8 MJup. The host star's estimated mass of 2.4-2.5 Msun places it among the most massive stars ever known to harbor an extrasolar planet or low-mass brown dwarf. While the mass of the companion is close to the deuterium burning limit, its mass ratio, orbital separation, and likely planet-like formation scenario imply that it may be best defined as a `Super-Jupiter' with properties similar to other recently discovered companions to massive stars., Comment: Accepted for publication in Astrophysical Journal Letters. 25 pages, 4 figures, 1 table

One of the key predictions of modeling from the IR excess of Herbig Ae stars is that for protoplanetary disks, where significant grain growth and settling has occurred, the dust disk has flattened to the point that it can be partially or largely shadowed by the innermost material at or near the dust sublimation radius. When the self-shadowing has already started, the outer disk is expected to be detected in scattered light only in the exceptional cases when the scale height of the dust disk at the sublimation radius is smaller than usual. High-contrast imaging combined with the IR spectral energy distribution allow us to measure the degree of flattening of the disk, as well as to determine the properties of the outer disk. We present polarimetric differential imaging in the H band obtained with Subaru/HiCIAO of one such system, MWC 480. The HiCIAO data were obtained at a historic minimum of the NIR excess. The disk is detected in scattered light from 0farcs2 to 1farcs0 (27.4-137 AU). Together with the marginal detection of the disk from 1998 February 24 by Hubble Space Telescope/NICMOS, our data constrain the opening half-angle for the disk to lie between 1fdg3 ≤θ ≤ 2fdg2. When compared with similar measures in CO for the gas disk from the literature, the dust disk subtends only ~30% of the gas disk scale height (H/R ~ 0.03). Such a dust disk is a factor of 5-7 flatter than transitional disks, which have structural signatures that giant planets have formed.

A GaN Schottky diode using Zr/Al/Mo/Au metal stack for Schttky contact has been newly developed. Turn-on (V on ) and breakdown voltages (V br ) are controllable with varying the annealing temperature. The fabricated diode shows the values V on , series resistance (R s ), capacitance (C 0 ), and V br to be 0.42 V, 4.2 Ω, 1.0 pF, and 24 V, respectively. These values indicate that 85% conversion efficiency is expected at 5.8 GHz in the rectenna circuit.

We have conducted a high‐resolution imaging and spectroscopic survey with the Subaru Telescope to study whether there is a maximum allowable separation of planetary‐mass objects. It resulted in the detection of a possible planetary‐mass (14 MJup) companion to a binary T Tauri star. The projected separation from its parent star is about 1,100 AU, the widest separation among planetary‐mass companion candidates detected so far.

III-nitride electron devices are attracting considerable attention for future wireless communication equipments and power electronics systems. This paper gives an overview on the state-of-the-art performance of AlGaN/GaN heterojunction FETs and describes some key issues concerning further improvements in the device performance. Focus is also on the future perspectives of III-nitride-based transistor applications.

Gallium nitride (GaN) is attracting considerable attention for microwave high-power transistor material as presented in W. L. Pribble et al. (2002), K. Joshin et al. (2003), Y. Okamoto et al. (2004), Y.-F. Wu et al. (2003) and M. Kuzuhara (2003). This is due to its unique material properties, including a wide bandgap leading to high-breakdown fields, a large high-field electron drift velocity leading to high speed, and the existence of polarization effects leading to high sheet charge density that exceeds 10/sup 13/cm/sup -2/. In this paper, recent progress of GaN FET technology for microwave power applications is described.

GaN has attractive physical properties, such as high saturation velocity, high breakdown electric field and good thermal conductivity. Owing to these inherent material properties, GaN and related alloys are attractive materials for high-speed, high-power and high-temperature electronic devices. For production process of electron devices such as recessed gate-AlGaN/GaN FET, a dry etching process is indispensable. Therefore, degradation of electrical properties due to the etching damage has to be considered to improve the device performance. In this work, influences of dry etching process for GaN on the electrical properties and the chemical properties of the surface were investigated.

An AlN/AlGaN high-electron-mobility transistor (HEMT) fabricated on a free-standing AlN substrate is demonstrated. A metal stack, composed of Zr/Al/Mo/Au, was found to show low contact resistivity for source and drain ohmic contacts. The fabricated AlN/AlGaN HEMT exhibited a maximum drain current of 38 mA/mm with a threshold voltage of -3.4 V. Negligible drain current degradation was observed at temperatures from 300 to 573 K, demonstrating that an AlN/AlGaN approach on an AlN substrate is promising for stable high-temperature operation.

This paper reports a high performance V-band MMIC dielectric resonator oscillator (DRO). The DRO utilizing a 0.15 /spl mu/m gate AlGaAs/InGaAs heterojunction FET has exhibited stabilized oscillation with low phase noise of -88 dBc/Hz at 100 kHz off-carrier and the output power of 3.7 dBm at 55.135 GHz. The oscillation frequency stability of -1.9 ppm//spl deg/C was obtained with a dielectric resonator of +3.3 ppm//spl deg/C temperature coefficient.

This letter describes a Ku-band power amplifier fabricated with a one-chip 0.45 /spl mu/m/spl times/16.8 mm GaAs-based heterojunction FET (HJFET), in which a 40.9 dBm (12.3 W) output power with 48% power-added efficiency (PAE) and 10.1 dB linear gain was achieved at 12 GHz. To our knowledge, this is the highest PAE, gain and output power combination achieved by a single FET power amplifier at this frequency. >

The present study is conducted to clarify the magnetic control characteristics of a particle-laden plasma jet impinging on a substrate for the improvement of a low pressure plasma spraying process and its controllable optimization. The plasma jet is described by Eulerian approach and each injected particle is described by Lagrangian approach respectively taking into account the compressible effect, variable transport properties and plasma-particle interactions, coupled with the Maxwell's equations. The effects of the location of the applied radio-frequency electromagnetic field, and of the injected particle size on the particle trajectory, particle velocity and its phase change are clarified by numerical simulation. It is concluded that the particle trajectory is influenced effectively and the injected particle temperature can be controlled strongly by applying the radio-frequency electromagnetic field to the nozzle. The reasonable agreement of particle velocity between calculation and experiment is observed.

We previously reported the direct detection of a low mass companion at a projected separation of 55+-2 AU around the B9 type star {\kappa} Andromedae. The properties of the system (mass ratio, separation) make it a benchmark for the understanding of the formation and evolution of gas giant planets and brown dwarfs on wide-orbits. We present new angular differential imaging (ADI) images of the Kappa Andromedae system at 2.146 (Ks), 3.776 (L'), 4.052 (NB 4.05) and 4.78 {\mu}m (M') obtained with Keck/NIRC2 and LBTI/LMIRCam, as well as more accurate near-infrared photometry of the star with the MIMIR instrument. We derive a more accurate J = 15.86 +- 0.21, H = 14.95 +- 0.13, Ks = 14.32 +- 0.09 mag for {\kappa} And b. We redetect the companion in all our high contrast observations. We confirm previous contrasts obtained at Ks and L' band. We derive NB 4.05 = 13.0 +- 0.2 and M' = 13.3 +- 0.3 mag and estimate Log10(L/Lsun) = -3.76 +- 0.06. We build the 1-5 microns spectral energy distribution of the companion and compare it to seven PHOENIX-based atmospheric models in order to derive Teff = 1900+100-200 K. Models do not set constrains on the surface gravity. ``Hot-start" evolutionary models predict masses of 14+25-2 MJup based on the luminosity and temperature estimates, and considering a conservative age range for the system (30+120-10 Myr). ``warm-start" evolutionary tracks constrain the mass to M >= 11 MJup. Therefore, the mass of {\kappa} Andromedae b mostly falls in the brown-dwarf regime, due to remaining uncertainties in age and mass-luminosity models. According to the formation models, disk instability in a primordial disk could account for the position and a wide range of plausible masses of {\kappa} And b., Comment: 20 pages, 16 figures, accepted for publication in Astronomy and Astrophysics on August 6, 2013

Publisher Summary This chapter discusses the important parameters that affect the electrical properties of ion-implanted gallium arsenide (GaAs) active regions, with particular emphasis on the post-implantation annealing procedures including rapid thermal annealing. A number of applications of furnace annealing to the formation of channel and n+ contact regions for GaAs field-effect transistor are presented. Commonly employed encapsulating films are reviewed in view of the desirable material requirements for GaAs annealing encapsulants. Emphasis is laid upon the activation of Si implants in GaAs, since Si implantation is currently being employed toward developing high-speed GaAs integrated circuits (ICs) throughout the world. The conditions required to achieve maximum electrical activation for Si-implanted channel regions are discussed in view of the type of encapsulants, encapsulating film thickness, and annealing temperature. Some methods for capless annealing under an arsenic pressure are also described, in which electrical activation dependence on arsenic partial pressure controlled by an ASH3 flow is discussed. The chapter discusses the advantages of rapid thermal annealing over conventional furnace annealing, together with a comparison with pulse annealing using Q-switched lasers or pulsed electron beams. The application of rapid thermal annealing to low-dose channel implants and high-dose n+ implants is also described. The formation of p+ regions by rapid thermal annealing is also presented for the fabrication of fully ion-implanted GaAs junction FET ICs. An effective method to minimize rapid thermal annealing-induced defects is presented. This method provides slip-free surface morphology, which is essential for uniform activation over the entire water.

Lattice matched InAlAs/InGaAs/InP heterojunction field-effect transistors (HJFETs), which have carrier supplying layers on and beneath the undoped InGaAs channel layer, have been successfully fabricated. A selective recess of the InGaAs channel edge at a mesa sidewall together with the use of a wide recess gate structure leads to a 5.7 V gate-drain breakdown voltage without kink effects. The fabricated HJFET with a 0.15 × 100 μm2 T-shaped gate exhibits a 700mA/mm maximum drain current, a voltage gain of 14, and a 345 GHz maximum frequency of oscillation.

Electron traps in n‐GaAs resulting from infrared rapid thermal annealing (IRTA) have been studied by deep‐level transient spectroscopy (DLTS). An electron trap with an activation energy of 0.20 eV from the conduction band, termed EN1, is introduced by IRTA above 800 °C. This trap formation is closely related to a rapid heating stage in an IRTA process. The EN1 concentration changes similarly to the concentration of the dominant midgap electron trap EL2 versus the variation of annealing temperature, annealing time, or encapsulating films. It is proposed that the IRTA‐related EN1 trap is ascribed to defect complexes, including AsGa antisite defects, such as VAsAsGa.

The intrinsic switching characteristics of tunneling hot electron transfer amplifier (THETA) devices has been simulated using a time-dependent ensemble Monte Carlo method. Results which show that there is no significant difference between the switch-on and switch-off times of THETA devices and that these switching times are always larger than the average total transit time through the base and the collector barrier are presented. The choice of the base width is important to determine the base transport factor, but it is not a direct measure of the intrinsic switching speed. The importance of velocity overshoot in the collector barrier region for ultra-high-speed device operation is demonstrated. An improved device structure that leads to subpicosecond switching speeds in the THETA structures is proposed. >

A Monte Carlo calculation has been performed to simulate the experiment of Heiblum and co‐workers [Phys. Rev. Lett. 55, 2200 (1985)], regarding ballistic electron transport and the electron transit time across the AlGaAs collector barrier region in AlGaAs/GaAs tunneling hot‐electron transfer amplifier devices. Ballistic transport is proven to be highly probable across a 1000‐A‐thick collector barrier under retarding field and hot‐electron injection conditions at 4.2 K. Applying accelerating fields in the barrier results in almost negligible ballistic fraction of the transmitted hot electrons because of electron scattering into the satellite valleys. This result seems paradoxical at first sight. However, it is typical for electronic transport in heterolayers and fully consistent with the interpretation of the experiments by Heiblum and co‐workers. There exists a negative collector‐base bias range which minimizes the collector barrier transit time, corresponding to the condition of large ballistic probabili...

Si‐implanted GaAs was successfully annealed with silicon oxynitride (SiOxNy) encapsulant. By using SiOxNy encapsulant with about 1.75 refractive index, a maximum electrical activation of 87%, which is 30–50% higher than that obtained after SiO2 or Si3N4 capped annealing, was achieved on Si‐implanted GaAs (5×1012 cm−2, 100 keV). In addition, electrical activation after SiOxNy capped annealing remains constant against the variation of film thickness up to 2300 A, indicating minimized interfacial stress between SiOxNy film and GaAs substrate. A maximum carrier concentration of 2.5×1018 cm−3, which is the highest value ever reported on Si‐implanted GaAs, was obtained after SiOxNy capped annealing for 7×1013 cm−2 dose. The controlled amount of Ga outdiffusion in combination with the reduced interfacial stress is considered to be responsible for this high electrical activation.

This is an autopsy case report of a 52-year-old woman with a brain abscess presenting as an intracerebral gas shadow on CT scan. She was admitted to our facility in June 1977, with disorientation and motor weakness of the right upper extremities. CT scan revealed two separate mass lesions in the frontal and occipital lobes on the left side. She was diagnosed as having metastatic carcinoma, and was treated by tumor removal, radiation therapy, and intraneoplastic local chemotherapy. Seventeen months later, she was readmitted with decreased mental activity, hemiconvulsion of the right side and high fever. CT scan revealed a peculiar round gas shadow on the left side of the temporal lobe. Ventricular drainage produced a cloudy cerebrospinal fluid with a protein concentration of more than 400 mg/dl and a leucocyte count of 138,200. An anaerobic culture of the ventricular cerebrospinal fluid revealed Escherichia coli. At that time, the lateral ventricle was irrigated several times with antibiotics. Unfortunately, however, she died one year after readmission. An autopsy was performed shortly after death, at which time serial coronal sectioning of the brain confirmed the CT scan findings presenting as an intracerebral gas shadow, and further demonstrated extension of the brain abscess from the left temporal lobe to the temporal horn of the lateral ventricle. The lesion in the left temporal lobe included yellowish pus with partially brownish capsules. A gas-containing brain abscess confirmed by CT scan and autopsy is rarely seen. The Hounsfield unit obtained from the abscess cavity by utilizing serial CT scan sometimes represents a condition requiring urgent treatment for brain abscess.

Recent activities in rapid thermal processing on III-V compound materials are reviewed with primary focus on its application to high-speed GaAs integrated circuits. Advantages of the rapid thermal processing are discussed, from the viewpoint of doping characteristics obtained both for n-type channel implants and for high dose n-type contact implants. Enhanced electrical activation is demonstrated by optimizing the encapsulating material employed for annealing high-dose Si implants. Not only these advantages, but also several problems, which should be solved before this technology can be fully utilized in industrial applications, are discussed. Special attention is devoted to improvement in the activation uniformity over a complete 2 inch diameter GaAs wafer.

GaAs ion-implanted layers for GaAs MESFET's have been successfully annealed by several seconds radiation from halogen lamps without any encapsulants. Si-implanted GaAs (5 × 1012cm-2, 100 keV)for an active layer annealed at 950°C for 2 seconds shows 40-50 % electrical activation with no signs of thermal dissociation. High carrier concentration profiles for S-implanted n+layers formed by this technique are also achieved with only slight impurity diffusion during annealing. For confirming the applicability of the annealing method, MESFET's with 1 µm gate length and 300 µm gate width were fabricated on the active layer formed by this technique. They show 20-30 % higher transconductance than that for MESFET's fabricated on conventional furnace annealed active layer. The higher transconductance is explained by steeper carrier concentration profile with higher peak carrier concentration in the active layer annealed by this method.

Rapid thermal process utilizing radiation from halogen lamps has been used to post-anneal ion-implanted GaAs. Annealing conditions for Si implants in GaAs are discussed from the view point of applying this technique to GaAs MESFET fabrication. Also, the properties of S and Mg implants in GaAs followed by rapid thermal annealing are comparatively studied with the results after conventional furnace annealing. High electrical activation and minimized implant diffusion for both low and high dose implants are the principal features of this technique. The fabricated MESFET showed much higher transconductance without any anomalous characteristics, indicating this technique to be a promising alternative to conventional furnace annealing.

For structural analyses with uncertainties, stochastic finite element method (SFEM) has been developed by Nakagiri, etc.[1] Based on a perturbation method, derivatives by probabilistic variables, means and dispersions of responces can be obtained. In this paper, the application of SFEM to a heat transfer problem with radiative boundary conditions is presented. A radiative b.c. yields a high nonlinearity and a perturbative solution for a limited case was obtained by AZIZ.[2] However, for practical FEM analyses a nonlinear perturbation FEM scheme has been anticipated. This paper introduces the developed scheme briefly and shows the sample results to validate it.