共查询到20条相似文献,搜索用时 15 毫秒
1.
Wireless Networks - Most existing connectivity-based localization algorithms require high node density which is unavailable in many large-scale sparse mobile networks. By analyzing large datasets... 相似文献
2.
Xiangdong Chen Kou-Chen Liu Ouyang Q.C. Jayanarayanan S.K. Banerjee S.K. 《Electron Devices, IEEE Transactions on》2001,48(9):1975-1980
We have fabricated strained SiGe vertical P-channel and N-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) by Ge ion implantation and solid phase epitaxy. No Si cap is needed in this process because Ge is implanted after gate oxide growth. The vertical MOSFETs are fabricated with a channel length below 0.2 μm without sophisticated lithography and the whole process is compatible with a regular CMOS process. The enhancement for the hole and electron mobilities in the direction normal to the growth plane of strained SiGe over that of bulk Si has been demonstrated in this vertical MOSFET device structure for the first time. The drain current for the vertical SiGe MOSFETs has been found to be enhanced by as much as 100% over the Si control devices and the drain current for the vertical SiGe NMOSFETs has been enhanced by 50% compared with the Si control de, ices on the same wafer. The electron mobility enhancement in the normal direction is not as significant as that for holes, which is in agreement with theoretical predictions 相似文献
3.
Lijuan Huang Chu J.O. Goma S.A. D'Emic C.P. Koester S.J. Canaperi D.F. Mooney P.M. Cordes S.A. Speidell J.L. Anderson R.M. Wong H.-S.P. 《Electron Devices, IEEE Transactions on》2002,49(9):1566-1571
N- and p-MOSFETs have been fabricated in strained Si-on-SiGe-on-insulator (SSOI) with high (15-25%) Ge content. Wafer bonding and H-induced layer transfer techniques enabled the fabrication of the high Ge content SiGe-on-insulator (SGOI) substrates. Mobility enhancement of 50% for electrons (with 15% Ge) and 15-20% for holes (with 20-25% Ge) has been demonstrated in SSOI MOSFETs. These mobility enhancements are commensurate with those reported for FETs fabricated on strained silicon on bulk SiGe substrates 相似文献
4.
Andrieu F. Ernst T. Ravit C. Jurczak M. Ghibaudo G. Deleonibus S. 《Electron Device Letters, IEEE》2005,26(10):755-757
This letter presents the first experimental study of the mobility in 50-nm gate length (L/sub G/) pMOSFETs highly strained by a contact etch stop layer. Thanks to an advanced characterization method, the mobility is in-depth studied versus the inversion charge density, the gate length and the temperature. The physical origin of the more than 50% mobility enhancement at L/sub G/=50 nm is proven to be the low effective mass of the top valence band rather than any scattering modification. This mobility gain is maintained even at high effective field. This explains the 30% I/sub ON/ enhancement at 50-nm gate length, which is among the best results at such a dimension. 相似文献
5.
Ti interdiffusion from the Ti/Pt/Au gate into the AlGaAs Schottky barrier layer (SBL) of 0.25-μm GaAs Pseudomorphic High Electron Mobility Transistors (PHEMTs) has been studied using the accelerated life testing technique. Based on measurements and modeling, analytical expressions for quantitative correlation between the positive pinch-off voltage (VP) shift as well as the saturation drain current (IDsat) decrease and the physical damage occurring during gate sinking has been developed. It is suggested that the main cause for device failure is the growth of the TiAs phase leading to the decrease in the SBL thickness. Additionally, it is suggested that VP may be used as a better indicator for device degradation than IDsat since it is linearly proportional to the degrading physical characteristic – the Schottky barrier layer thickness. 相似文献
6.
An n -channel SOI-MOSFET fabricated on a very thin (500 Å) SOI substrate exhibited no detectable drain-current overshoot for various gate turn-on pulses. The reason can be ascribed to the suppression of the floating substrate effect, brought about by the quick decay of excess holes 相似文献
7.
Polarity dependence of the gate tunneling current in dual-gate CMOSFETs is studied over a gate oxide range of 2-6 nm. It is shown that, when measured in accumulation, the Ig versus Vg characteristics for the p+/pMOSFET are essentially identical to those for the n+/nMOSFET; however, when measured in inversion, the p+/pMOSFET exhibits much lower gate current for the same |Vg|. This polarity dependence is explained by the difference in the supply of the tunneling electrons. The carrier transport processes in p+/pMOSFET biased in inversion are discussed in detail. Three tunneling processes are considered: (1) valence band hole tunneling from the Si substrate; (2) valence band electron tunneling from the p+-polysilicon gate; and (3) conduction band electron tunneling from the p+-polysilicon gate. The results indicate that all three contribute to the gate tunneling current in an inverted p+/pMOSFET, with one of them dominating in a certain voltage range 相似文献
8.
Nayfeh H.M. Leitz C.W. Pitera A.J. Fitzgerald E.A. Hoyt J.L. Antoniadis D.A. 《Electron Device Letters, IEEE》2003,24(4):248-250
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. 相似文献
9.
J. M. McGregor T. Manku J. -P. Noël D. J. Roulston A. Nathan D. C. Houghton 《Journal of Electronic Materials》1993,22(3):319-321
Measured in-plane hole drift and Hall mobilities in heavily boron-doped strained Si1−xGex layers are reported. In the range of boron dopings examined (1.5–2.1 × 1019 cm−3), the drift mobility is seen to increase with increasing germanium fraction. The Hall mobility decreases with increasing
germanium fraction.
Presented at the 1992 EMC, Boston. 相似文献
10.
Drain-current transients of GaAs MESFET's with deep donors “EL2” in the semi-insulating substrate are simulated in the range t=10-13 to 102 s. It is shown that in the drain step responses, there exists a “quasi-steady state” where the deep donors do not respond to the voltage change and the drain currents become constant temporarily. The drain currents begin to decrease or increase gradually when the deep donors begin to capture or emit electrons, reaching real steady-state values. I-V curves are quite different between the “quasi-steady state” and the steady state. Therefore, the deep donors in the semi-insulating substrate can be causes of drain-current drifts and hysteresis in I-V curves. Effects of introducing a p-buffer layer are also studied. It is concluded that the use of a low acceptor density semi-insulating substrate combined with introducing a p-buffer layer is effective to minimize the unfavorable phenomena and to utilize high performances of GaAs MESFET's 相似文献
11.
A new model is proposed to describe the electron mobility enhancement in strained Si MOSFETs inversion layers using the variational wave functions in the triangular potential approximation. Phonon scattering and surface roughness scattering are included in this model and electron mobility enhancements due to the suppression of these two scatterings are accounted for, respectively. A process-dependent interface parameter is introduced to fit with various technologies. Results from the model show good agreement with experiments for different Ge mole fractions and for a wide range of vertical effective field and temperature. The model is very interesting for implementation in conventional device simulators. 相似文献
12.
In order to quantitatively characterize the enhancement of hole mobility of strained silicon under different stress intensity conditions, changes of hole effective mass should be studied. In the paper, strained silicon under in-plane biaxially tensile strain based on (0 0 1) substrate and longitudinal uniaxially compressive strain along 〈1 1 0〉 are investigated thoroughly. By solving the Hamiltonian of valence band using K·P model, we can obtain the relationship of density of state effective mass (mDOS), conductivity effective mass (mC) and splitting energy in valence band energy with stress intensity for both biaxially tensile strain and uniaxially compressive strain. For the stress intensity less than 1 GPa, the paper presents the models of enhancement factor of hole mobility under the biaxially tensile strain and uniaxially compressive strain. The results show that biaxially tensile strain of silicon cannot enhance hole mobility under low stress intensity, while uniaxially compressive stress of silicon can enhance hole mobility greatly. 相似文献
13.
Results of the lattice drift mobility in strained and unstrained SiGe alloys are reported for Ge fractions, 0.0⩽x ⩽1.0. The mobilities are calculated using acoustic, optical, and alloy scattering mechanisms. Due to the strain-induced symmetry reduction in the band structure of Si1-xGex, the mobility is found to be a tensor with two distinct components parallel and perpendicular to the growth plane. Assuming that the scattering mechanisms are independent of the strain, the strained mobility increases exponentially with increasing Ge content, for x =0.3 相似文献
14.
Manku T. McGregor J.M. Nathan A. Roulston D.J. Noel J.-P. Houghton D.C. 《Electron Devices, IEEE Transactions on》1993,40(11):1990-1996
Results of the drift hole mobility in strained and unstrained SiGe alloys are reported for Ge fractions varying from 0 to 30% and doping levels of 1015-1019 cm-3. The mobilities are calculated taking into account acoustic, optical, alloy, and ionized-impurity scattering. The mobilities are then compared with experimental results for a boron doping concentration of 2×1019 cm-3. Good agreement between experimental and theoretical values is obtained. The results show an increase in the mobility relative to that of silicon 相似文献
15.
Takahashi M. Ohno T. Sakakibara Y. Takayama K. 《Electron Devices, IEEE Transactions on》2001,48(7):1380-1385
Fully-depleted 20-nm SOI complementary metal-oxide-semiconductor field effect transistors (CMOSFETs) were successfully fabricated without a raised source/drain (S/D) structure, instead using low-temperature selective tungsten CVD (SWCVD) technology that can reduce the S/D series resistance. The thickness of the residual SOI layer under the W-clad layer in the S/D region was 6 nm for an nMOSFET and 9 nm for a pMOSFET. For 0.15-μm-gate CMOSFETs, the subthreshold swings were 70 and 75 mV/dec for the nMOSFET and pMOSFET, respectively. The effectiveness of SWCVD technology when applied to ultrathin SOI devices was confirmed by small Si consumption and good continuity between the W and SOI layers. We expect that the S/D series resistance can be reduced to less than 1 kΩ-μm by optimizing the S/D implantation conditions 相似文献
16.
《Microelectronics Reliability》2014,54(12):2668-2674
We have investigated the role of temperature in the degradation of GaN High-Electron-Mobility-Transistors (HEMTs) under high-power DC stress. We have identified two degradation mechanisms that take place in a sequential manner: the gate leakage current increases first, followed by a decrease in the drain current. Building on this observation, we demonstrate a new scheme to extract the activation energy (Ea) of device degradation from step-temperature measurements on a single device. The Ea’s we obtain closely agree with those extracted from conventional accelerated life test experiments on a similar device technology. 相似文献
17.
W. Yu B. Zhang Q.T. Zhao J.-M. HartmannD. Buca A. NichauR. Lupták J.M. LopesS. Lenk M. LuysbergK.K. Bourdelle X. WangS. Mantl 《Solid-state electronics》2011,62(1):185-188
Strained SiGe quantum well p-MOSFETs with LaLuO3 higher-k dielectric were fabricated and characterized. The strained Si/strained Si0.5Ge0.5/strained SOI heterostructure transistors showed good output and transfer characteristics with an Ion/Ioff ratio of 105. The extracted hole mobility shows an enhancement of about 2.5 times over Si universal hole mobility and no degradation compared to HfO2 or even SiO2 gate dielectric devices. 相似文献
18.
Tzu-Juei Wang Chih-Hsin Ko Shoou-Jinn Chang San-Lein Wu Ta-Ming Kuan Wen-Chin Lee 《Electron Devices, IEEE Transactions on》2008,55(2):572-577
This paper reports the influences of uniaxial mechanical stress on the reverse-biased source/drain to substrate junction leakage of state-of-the-art 65 nm CMOS transistors. For n-channel metal-oxide-semiconductor (NMOS) transistors, the band-to-band tunneling (BTBT) dominates the junction leakage current due to heavily doped junction and pocket implants. However, for p-channel metal-oxide-semiconductor (PMOS) transistors with embedded SiGe source/drain, the leakage current is found to result from both BTBT and generation current due to defects generated in the SiGe layer and at the SiGe/Si interface. A four-point bending technique is used to apply mechanical uniaxial stress on NMOS and PMOS devices along the longitudinal direction. It was found that the leakage current of both devices increases (decreases) with applied uniaxial compressive (tensile) stress, and that the strain sensitivity of the junction leakage of NMOS transistors is much weaker than that of PMOS transistors. By combining the bending technique with process strained Si (PSS) technology, additional stress was applied to NMOS and PMOS with high built-in stress to investigate the characteristics of junction leakage under extremely high uniaxial stress. It is shown that uniaxial tensile stress can both enhance the NMOS device performance and decrease the junction leakage. However, for the PMOS, there exists a tradeoff between boosting the transistor performance and decreasing the junction leakage current, so there is a limit in the amount of compressive stress that can be beneficially applied. 相似文献
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20.
A study into the effect of the strain on a tapered fibre acoustooptic filter is presented. The centre wavelengths of the resonances are dramatically affected by strain: >500 nm tunability range has been obtained for a maximum applied strain of 1.3×10-2 相似文献