The Experts below are selected from a list of 30459 Experts worldwide ranked by ideXlab platform
Shinichi Takagi - One of the best experts on this subject based on the ideXlab platform.
-
experimental evaluation of coulomb scattering limited Inversion Layer mobility of n type metal oxide semiconductor field effect transistors on si 100 110 and 111 surfaces impact of correlation between conductivity mass and normal mass
Japanese Journal of Applied Physics, 2010Co-Authors: Yukio Nakabayashi, Takamitsu Ishihara, Toshinori Numata, Ken Uchida, Shinichi TakagiAbstract:The Inversion-Layer electron mobility limited by Coulomb scattering due to interface states (µit) and substrate impurities (µsub) are experimentally evaluated on Si n-type metal–oxide–semiconductor field-effect transistors (MOSFETs) at the surfaces of Si(100), (110), and (111). The Inversion-Layer mobility is measured by the split C–V method and µit and µsub are extracted using Matthiessen's rule. µit exhibits almost the same behavior irrespective of the different surface orientations, while µsub has the surface orientation dependence. The very weak surface orientation dependence of µit are due to the correlation between the Inversion Layer thickness (Zave) determined by the normal mass (mz) and the weighed average value of conductivity mass (mc_ave) under multi valley occupation. The surface orientation dependence of µsub is basically explained by the mc_ave difference.
-
effects of si passivation on ge metal insulator semiconductor interface properties and Inversion Layer hole mobility
Applied Physics Letters, 2008Co-Authors: Noriyuki Taoka, Masatomi Harada, Yoshimi Yamashita, Toyoji Yamamoto, Naoharu Sugiyama, Shinichi TakagiAbstract:The impact of Si passivation (SP) on Ge metal-insulator-semiconductor interface properties and the Inversion-Layer mobility of Ge p-type metal-insulator-semiconductor field effect transistors (PMISFETs) were investigated by using the devices with different thicknesses of the SP Layers. SP was effective in decreasing the total charged centers instead of the interface traps. As a result, the Inversion-Layer hole mobility of the Ge MISFET was significantly improved by introducing the SP Layers of the appropriate thickness. This improvement is attributable to the reduction of the amount of the interface charges and the separation of the positions of mobile carriers and the interface charges by the SP Layers.
-
high performance 60 nm gate length germanium p mosfets with ni germanide metal source drain
International Electron Devices Meeting, 2007Co-Authors: T Yamamoto, Noriyuki Taoka, Yoshimi Yamashita, M Harada, Keiji Ikeda, K Suzuki, O Kiso, N Sugiyama, Shinichi TakagiAbstract:This paper demonstrates the successful fabrication of sub-100 nm Ge pMOSFETs with NiGe MSD and the high device performance, for the first time. It is also revealed that impurity profile engineering is still effective in controlling the electrical characteristics of short channel Ge MOSFET and that the concept of the universality for the Inversion-Layer mobility does hold even for Ge p-MOSFETs.
-
influences of buried oxide interface on Inversion Layer mobility in ultra thin soi mosfets
IEEE Transactions on Electron Devices, 2002Co-Authors: Junji Koga, Shinichi Takagi, A ToriumiAbstract:This paper reports on a study of the Inversion-Layer mobility in n-channel Si MOSFETs fabricated on a silicon-on-insulator (SOI) substrate. In order to make clear the influences of the buried-oxide interface on the Inversion-Layer mobility in ultra-thin film SOI transistors, SOI wafers of different quality at the buried-oxide interface were prepared, and the mobility behaviors were compared quantitatively. The transistors with a relatively thick SOI film exhibited the universal relationship between the effective mobility and the effective normal field, regardless of the buried-oxide interface quality. It was found, however, that Coulomb scattering due to charged centers at the backside interface between SOI films and buried oxides has great influence on the effective mobility in the thin SOI thickness region, depending on the buried-oxide interface quality. This means that Coulomb scattering due to charged centers at the buried-oxide interface can degrade the mobility with decreasing SOI thickness, unless the SOI wafer quality at the buried-oxide interface is controlled carefully.
-
experimental evidence of Inversion Layer mobility lowering in ultrathin gate oxide metal oxide semiconductor field effect transistors with direct tunneling current
Japanese Journal of Applied Physics, 2002Co-Authors: Shinichi Takagi, M TakayanagiAbstract:In this paper, the results of the direct measurement of Inversion-Layer mobility for metal-oxide-semiconductor field-effect-transistors (MOSFETs) with ultrathin gate oxides, based on the split C–V method are reported. It was demonstrated that Inversion-Layer electron mobility can be accurately measured for MOSFETs with gate oxide thickness of down to 1.5 nm by the split C–V method with modified measurement of drain conductance under optimum device size and measurement conditions. It was found that, when gate oxide thickness is less than 3 nm, the mobility deceases in the low surface carrier concentration (effective field) region with a decrease in gate oxide thickness and that this mobility lowering becomes smaller in the higher surface carrier concentration (effective field) region. It was also found that mobility limited by some additional scattering observed in thin gate oxides has almost no surface carrier concentration dependence.
Richard P Turco - One of the best experts on this subject based on the ideXlab platform.
-
air pollutant transport in a coastal environment ii three dimensional simulations over los angeles basin
Atmospheric Environment, 1995Co-Authors: Richard P TurcoAbstract:Abstract The: air quality problems in the Los Angeles basin are related to the local climate. A strong temperature Inversion and stagnant synoptic conditions associated with the Pacific high-pressure system favor the generation of severe air pollution episodes. Sea-breezes and mountain-induced flows play an important role: in controlling pollutant transport over the basin. The distributions of pollutants over the basin display complicated three-dimensional patterns, including distinct elevated Layers. A three-dimensional meteorological model is used to simulate air flow patterns and pollutant transport in the Los Angeles basin under such conditions. The complex simulated flows are analyzed to explain the origin of the observed pollution Layers. Pollutants found in the afternoon mixed Layer may be dispersed to three different regions: the high desert to the east and north of the Los Angeles basin; the free troposphere above the temperature Inversion; and within the temperature Inversion Layer itself. Several mechanisms transfer pollution into the Inversion Layer. Convergence zones in the San Fernando Valley and near Lake Elsinore lift polluted air into the Inversion. A coupled sea-bree~eymountain-flow circulation along the southwest flank of the Santa Ana Mts creates pollution Layers that extend westward over the coastal plain and offshore. The afternoon pollution Layers frequently observed in the western Los Angeles basin are caused by the sea-breeze circulation or the coupled sea-breeze/mountain-flow circulation over the south slope of the San Gabriel Nlts. As the boundary Layer stabilizes during the early evening, Layers of polluted air are left suspended over the eastern basin. Pollutants trapped in the Inversion Layer act as a reservoir of poor-quality air for the basin, and may contribute to extreme pollutant concentrations seen after several days of stagnant air.
-
air pollutant transport in a coastal environment part i two dimensional simulations of sea breeze and mountain effects
Journal of the Atmospheric Sciences, 1994Co-Authors: Richard P TurcoAbstract:Over the southern California coastal region, observations of the vertical distributions of pollutants show that maximum concentrations can occur within temperature Inversion Layers well above the surface. A mesoscale model is used to study the dynamical phenomena that cause such Layers, including sea breezes and mountain flows, and to study the characteristics of air pollutant transport in a coastal environment capped by a temperature Inversion. The mathematical and physical structure of the model is described. Two-dimensional simulations corresponding to four configurations of coastal plains and mountains are discussed. The simulations reveal that pollutant transport over a coastal plain is strongly influenced by the topographic configuration, including the height of coastal mountains and their distance from the coastline. Sea breezes induced by land-sea thermal contrasts, as well as upslope winds induced along mountain flanks, both create vertical transport that can lead to the formation of elevated pollution Layers. The sea-breeze circulation generates pollution Layers by undercutting the mixed Layer and lofting pollutants into the stable Layer. Heating of mountain slopes acts to vent pollutants above the mountain ridge during the day; during the evening, pollutants can be injected directly into the Inversion Layer from the decaying upslope flows. In a land-sea configuration with mountains close to the coastline, the sea breeze and heated-mountain flow are strongly coupled. In the afternoon, this interaction can produce upslope flow from which polluted air is detrained into the Inversion Layer as a return circulation. When the mountains lie farther inland, however, pollutants may be trapped aloft when the mixed Layer stabilizes in the late afternoon. As the nocturnal boundary Layer forms over the coast in the evening, polluted mixed-Layer air is effectively left behind in the Inversion Layer. In the Los Angeles Basin, the formation mechanism for elevated polluted Layers is most similar to our cases with inland mountains.
H Tango - One of the best experts on this subject based on the ideXlab platform.
-
on the universality of Inversion Layer mobility in si mosfet s part i effects of substrate impurity concentration
IEEE Transactions on Electron Devices, 1994Co-Authors: Shinichi Takagi, A Toriumi, M Iwase, H TangoAbstract:This paper reports the studies of the Inversion Layer mobility in n- and p-channel Si MOSFET's with a wide range of substrate impurity concentrations (10/sup 15/ to 10/sup 18/ cm/sup -3/). The validity and limitations of the universal relationship between the Inversion Layer mobility and the effective normal field (E/sub eff/) are examined. It is found that the universality of both the electron and hole mobilities does hold up to 10/sup 18/ cm/sup -3/. The E/sub eff/ dependences of the universal curves are observed to differ between electrons and holes, particularly at lower temperatures. This result means a different influence of surface roughness scattering on the electron and hole transports. On substrates with higher impurity concentrations, the electron and hole mobilities significantly deviate from the universal curves at lower surface carrier concentrations because of Coulomb scattering by the substrate impurity. Also, the deviation caused by the charged centers at the Si/SiO/sub 2/ interface is observed in the mobility of MOSFET's degraded by Fowler-Nordheim electron injection. >
-
on the universality of Inversion Layer mobility in si mosfet s part ii effects of surface orientation
IEEE Transactions on Electron Devices, 1994Co-Authors: Shinichi Takagi, A Toriumi, M Iwase, H TangoAbstract:For part I see ibid., vol.41, no.12, pp.2357-62 (1994). This paper reports the studies of the Inversion Layer mobilities in n-channel MOSFET's fabricated on Si wafers with three surface orientations ([100], [110], and [111]) from the viewpoint of the universal relationship against the effective field, E/sub eff/(=q(N/sub dpl/+/spl eta//spl middot/N/sub s/)//spl epsi/Si). It is found that the universality does hold for the electron mobilities on [110] and [111], when the value of /spl eta/ is taken to be 1/3, different from the electron mobility on [100], where /spl eta/ is 1/2. Also, the E/sub eff/ dependence of the electron mobility is found to differ among [100], [110], and [111] surfaces. This is attributed to the differences in the E/sub eff/ dependence of the mobility limited by surface roughness scattering among the orientations. The origins of E/sub eff/ and /spl eta/ are discussed on the basis of the relaxation time approximation for a 2DEG (2-dimensional electron gas). While the surface orientation dependence of /spl eta/ in phonon scattering can be understood in terms of the subband occupation, it is found that the theoretical formulation of surface roughness scattering, used currently, needs to be refined in order to explain the differences in E/sub eff/ dependence and the value of /spl eta/ among the three orientations. >
D A Antoniadis - One of the best experts on this subject based on the ideXlab platform.
-
influence of high channel doping on the Inversion Layer electron mobility in strained silicon n mosfets
IEEE Electron Device Letters, 2003Co-Authors: Hasan M Nayfeh, Arthur J Pitera, Judy L Hoyt, Eugene A Fitzgerald, C W Leitz, D A AntoniadisAbstract:In this letter, we investigate the dependence of electron Inversion Layer mobility on high-channel doping required for sub-50-nm MOSFETs in strained silicon (Si), and we compare it to co-processed unstrained Si. For high vertical effective electric field E/sub eff/, the electron mobility in strained Si displays universal behavior and shows enhancement of 1.5-1.7/spl times/ compared to unstrained Si. For low E/sub eff/, the mobility for strained Si devices decreases toward the unstrained Si data due to Coulomb scattering by channel dopants.
-
electron Inversion Layer mobility in strained si n mosfets with high channel doping concentration achieved by ion implantation
Device Research Conference, 2002Co-Authors: Hasan M Nayfeh, Arthur J Pitera, Judy L Hoyt, Eugene A Fitzgerald, C W Leitz, D A AntoniadisAbstract:Inversion Layer mobility measurements in strained-Si n-MOSFETs fabricated using a typical MOSFET process including high temperature steps and with various channel doping concentrations, achieved by boron ion implantation, are compared with co-processed bulk-Si n-MOSFETs. It is found that a near-universal mobility relationship with vertical effective electric field, E/sub eff/, exists for strained-Si and bulk-Si n-MOSFETs for all channel implant doses in this study. Significant mobility enhancement for E/sub eff/ up to 2 MV/cm (1.5-1.7 x) is obtained for channel doping concentrations ranging from 10/sup 17/-6 /spl times/ 10/sup 18/ cm/sup -3/.
Thomas S Megeath - One of the best experts on this subject based on the ideXlab platform.
-
the 3 6 8 0 μm broadband emission spectrum of hd 209458b evidence for an atmospheric temperature Inversion
The Astrophysical Journal, 2008Co-Authors: Heather A Knutson, Adam Burrows, David Charbonneau, Lori E Allen, Thomas S MegeathAbstract:We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet HD 209458b at 3.6, 4.5, 5.8, and 8.0 μm using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We observe a single secondary eclipse simultaneously in all four bandpasses and find relative eclipse depths of 0.00094 ± 0.00009, 0.00213 ± 0.00015, 0.00301 ± 0.00043, and 0.00240 ± 0.00026, respectively. These eclipse depths reveal that the shape of the inferred emission spectrum for the planet differs significantly from the predictions of standard atmosphere models; instead, the most plausible explanation would require the presence of an Inversion Layer high in the atmosphere leading to significant water emission in the 4.5 and 5.8 μm bandpasses. This is the first clear indication of such a temperature Inversion in the atmosphere of a hot Jupiter, as previous observations of other planets appeared to be in reasonably good agreement with the predictions of models without such an Inversion Layer.
-
the 3 6 8 0 micron broadband emission spectrum of hd 209458b evidence for an atmospheric temperature Inversion
arXiv: Astrophysics, 2007Co-Authors: Heather Knutson, Adam Burrows, David Charbonneau, Lori E Allen, Thomas S MegeathAbstract:We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet HD 209458b at 3.6, 4.5, 5.8, and 8.0 microns using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We observe a single secondary eclipse simultaneously in all four bandpasses and find relative eclipse depths of 0.00094 +/- 0.00009, 0.00213 +/- 0.00015, 0.00301 +/- 0.00043, and 0.00240 +/- 0.00026, respectively. These eclipse depths reveal that the shape of the inferred emission spectrum for the planet differs significantly from the predictions of standard atmosphere models; instead the most plausible explanation would require the presence of an Inversion Layer high in the atmosphere leading to significant water emission in the 4.5 and 5.8 micron bandpasses. This is the first clear indication of such a temperature Inversion in the atmosphere of a hot Jupiter, as previous observations of other planets appeared to be in reasonably good agreement with the predictions of models without such an Inversion Layer.
