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Mizuno T.,Kanagawa University | Hasegawa M.,Kanagawa University | Ikeda K.,MIRAI Toshiba | Nojiri M.,Japan National Institute of Advanced Industrial Science and Technology | Horikawa T.,MIRAI NIRC
Japanese Journal of Applied Physics | Year: 2011

We have experimentally studied an abrupt lateral-relaxed/strained layer heterojunction for ballistic complementary metal oxide semiconductor (CMOS) transistors, which is fabricated by a local O+ ion-induced relaxation technique for strained semiconductors on a buried oxide layer. We have demonstrated that strained substrates in various conditions are suddenly relaxed at a critical recoil energy of O+ ions at the strained semiconductor/buried oxide layer interface. Moreover, after O+ ion implantation into strained substrates with a SiO2 mask as well as postannealing processes, we have successfully formed lateral relaxed/strained Si layers with an abrupt strain distribution at the mask edge, according to Raman spectroscopy analysis of implanted strained substrates. In addition, strained Si layers even under the 50-nm length stripe SiO2 mask region can still keep over 60% of the strain value in strained Si layers with a large area. © 2011 The Japan Society of Applied Physics.

Taoka N.,Japan National Institute of Advanced Industrial Science and Technology | Taoka N.,University of Tokyo | Ikeda K.,MIRAI Toshiba | Mizubayashi W.,Japan National Institute of Advanced Industrial Science and Technology | And 5 more authors.
Journal of Applied Physics | Year: 2011

To accurately evaluate the Ge metal-insulator-semiconductor (MIS) interface trap density (Dit) by employing the conventional method for Si MIS capacitors on Ge MIS capacitors, we have investigated the impact of majority and minority carrier responses on C-V curves and/or the energy distributions of Dit. It is found that the high-frequency C-V curve, which does not include the majority carrier response with interface traps, cannot be obtained near room temperature (RT) even at 1 MHz. Therefore, to accurately evaluate the Dit values using the Terman method, the C-V curve has to be measured at an appropriate temperature. Furthermore, in the conductance method, evaluations by the model including the narrow bandgap effects are needed to obtain accurate Dit of the Ge MIS interface near RT. Through such accurate evaluation, the interface properties with different kinds of interfacial layers have been investigated. Although the GeO2/Ge interface has a low Dit and a fixed oxide charge density, the total charged center density contributing to surface potential fluctuation is larger than those for the GeOx/Ge and GeOxNy/Ge interfaces. These results suggest that the evaluation methods of the Ge MIS interface taking into account the appropriate carrier responses is quite important to obtain accurate Ge MIS interface properties. © 2011 American Institute of Physics.

Poborchii V.,Japan National Institute of Advanced Industrial Science and Technology | Poborchii V.,RAS Ioffe Physical - Technical Institute | Tada T.,Japan National Institute of Advanced Industrial Science and Technology | Usuda K.,MIRAI Toshiba | Kanayama T.,Japan National Institute of Advanced Industrial Science and Technology
Applied Physics Letters | Year: 2011

Using a high-numerical-aperture lens, we studied strain relaxation in the [110]-oriented strained-silicon-on-insulator (SSOI) stripes. A complete set of Si optical phonon Raman bands was observed. For a 50 nm thick SSOI, the symmetrical biaxial tensile stress in a relatively wide stripe is found to transform to the uniaxial [110] stress at its edge. The same uniaxial stress is observed in the narrow stripes with widths <200 nm, the value, probably, being a critical width for a complete SSOI transverse stress relaxation. © 2011 American Institute of Physics.

Mizuno T.,Kanagawa University | Mizoguchi N.,Kanagawa University | Tanimoto K.,Kanagawa University | Yamauchi T.,Kanagawa University | And 3 more authors.
Japanese Journal of Applied Physics | Year: 2010

We have studied new abrupt-source-relaxed/strained semiconductor- heterojunction structures for quasi-ballistic complementary metal-oxide- semiconductor (CMOS) devices, by locally controlling the strain of a single strained semiconductor. Appling O+ ion implantation recoil energy to the strained semiconductor/buried oxide interface, Raman analysis of the strained layers indicates that we have successfully relaxed both strained-Si-on-insulator (SSOI) substrates for n-MOS and SiGe-on-insulator (SGOI) substrates for p-MOS without polycrystallizing the semiconductor layers, by optimizing O+ ion implantation conditions. As a result, it is considered that the source conduction and valence band offsets ΔE C and ΔEV can be realized by the energy difference in the source Si/channel-strained Si and the source-relaxed SiGe/channelstrained SiGe layers, respectively. The device simulator, considering the tunneling effects at the source heterojunction, shows that the transconductance of sub-10 nm source heterojunction MOS transistors (SHOT) continues to increase with increasing ΔEC. Therefore, SHOT structures with the novel source heterojunction are very promising for future quasi-ballistic CMOS devices. © 2010 The Japan Society of Applied Physics.

Ono M.,MIRAI Toshiba | Tezuka T.,MIRAI Toshiba
Japanese Journal of Applied Physics | Year: 2010

In this study, electron mobility and band-gap energy in bulk Ge for arbitrary current directions under both biaxial and uniaxial tensile strains are thoroughly investigated by numerical calculations in order to identify the optimum strain configuration and channel direction. The results revealed a trade-off between a high electron mobility and a wide band gap. The maximum electron mobility of 5,680 cm2 V-1 s-1 was obtained under isotropic biaxial tensile strain in the (111) plane, while the narrowest band gap of 0.436 eV was obtained. In order to study cases with more realistic strain configurations such as process-induced strain, electron mobility and band-gap energy under anisotropic biaxial and uniaxial strains were also studied. It was shown that a combination of the [110] channel direction with uniaxial tensile strain parallel to the channel provides the most technically preferable solution, realizing an electron mobility of 5,626 cm 2 V-1 s-1 and a band-gap energy of 0.512 eV. © 2010 The Japan Society of Applied Physics.

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