| 1. |
- Li, Chen, et al.
(författare)
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Rapid Four-Point Sweeping Method to Investigate Hysteresis of MoS2 FET
- 2020
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Ingår i: IEEE Electron Device Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0741-3106 .- 1558-0563. ; 41:9, s. 1356-1359
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Tidskriftsartikel (refereegranskat)abstract
- Hysteresis is a frequently observed phenomenon in the transfer characteristics of thin film transistors. Charge trapping/de-trapping processes of gate oxide and gate-channel interface are commonly known to be the origin of hysteresis and correlated to low frequency noise (LFN) properties of the devices. In this letter, a rapid four-point sweeping method (RFSM) is proposed to reveal the dependence of hysteresis, as well as the distribution of effective trap density on sweeping rate and gate bias range. Based on the RFSM, the hysteresis properties of four-layer MoS2 FETs are studied in detail. The experimental results demonstrate that the hysteresis and trap density at different frequencies and gate voltages, which could further roughly map the traps with different time constants and energy depths, can be obtained by the simple RFSM. Trap density estimated by RFSM shows a comparable range with that extracted from LFN, indicating that the traps inducing the hysteresis may also cause LFN.
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| 2. |
- Luo, Jun, et al.
(författare)
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Interaction of NiSi with dopants for metallic source/drain applications
- 2010
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 28:1, s. C1I1-C1I11
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Tidskriftsartikel (refereegranskat)abstract
- This work has a focus on NiSi as a possible metallic contact for aggressively scaled complementary metal oxide semiconductor devices. As the bulk work function of NiSi lies close to the middle of Si bandgap, the Schottky barrier height (SBH) of NiSi is rather large for both electron (similar to 0.65 eV) and hole (similar to 0.45 eV). Different approaches have therefore been intensively investigated in the literature aiming at reducing the effective SBH: dopant segregation (DS), surface passivation (SP), and alloying, in order to improve the carrier injection into the conduction channel of a field-effect transistor. The present work explores DS using B and As for the NiSi/Si contact system. The effects of C and N implantation into Si substrate prior to the NiSi formation are examined, and it is found that the presence of C yields positive effects in helping reduce the effective SBH to 0.1-0.2 eV for both conduction polarities. A combined use of DS or SP with alloying could be considered for more effective control of effective SBH, but an examination of undesired compound formation and its probable consequences is necessary. Furthermore, an analysis of the metal silicides that have a small "intrinsic" SBH reveals that only a very small number of them are of practical interest as most of the silicides require either a high formation temperature or possess a high specific resistivity.
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| 3. |
- Luo, Jun, et al.
(författare)
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Surface-energy triggered phase formation and epitaxy in nanometer-thick Ni1-xPtx silicide films
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 96:3
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Tidskriftsartikel (refereegranskat)abstract
- The formation of ultrathin silicide films of Ni1-xPtx at 450-850 degrees C is reported. Without Pt (x=0) and for t(Ni)< 4 nm, epitaxially aligned NiSi2-y films readily grow and exhibit extraordinary morphological stability up to 800 degrees C. For t(Ni)>= 4 nm, polycrystalline NiSi films form and agglomerate at lower temperatures for thinner films. Without Ni (x=1) and for t(Pt)=1-20 nm, the annealing behavior of the resulting PtSi films follows that for the NiSi films. The results for Ni1-xPtx of other compositions support the above observations. Surface energy is discussed as the cause responsible for the distinct behavior in phase formation and morphological stability.
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| 4. |
- Gao, Xindong, et al.
(författare)
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Epitaxy of Ultrathin NiSi2 Films with Predetermined Thickness
- 2011
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Ingår i: Electrochemical and solid-state letters. - : The Electrochemical Society. - 1099-0062 .- 1944-8775. ; 14:7, s. H268-H270
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a proof-of-concept process for tunable, self-limiting growth of ultrathin epitaxial NiSi2 films on Si (100). The process starts with metal sputter-deposition, followed by wet etching and then silicidation. By ionizing a fraction of the sputtered Ni atoms and biasing the Si substrate, the amount of Ni atoms incorporated in the substrate after wet etching can be controlled. As a result, the thickness of the NiSi2 films is increased from 4.7 to 7.2 nm by changing the nominal substrate bias from 0 to 600 V. The NiSi2 films are characterized by a specific resistivity around 50 mu Omega cm.
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| 5. |
- Zhang, Zhen, et al.
(författare)
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A novel self-aligned process for platinum silicide nanowires
- 2006
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 83:11-12, s. 2107-2111
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Tidskriftsartikel (refereegranskat)abstract
- Directly accessible, ultralong, uniform platinum silicide nanowires in PtSi and Pt2Si are mass-fabricated by combining a sidewall transfer lithography (STL) technology and a self-aligned silicide process. The STL technology is based on standard Si technology. The self-aligned platinum silicide (PtSix) process consists of two sequential steps in a single run: a silicidation step in N-2 to ensure a controllable silicide formation followed by an oxidation step in O-2 to form a reliable protective SiOx layer on top of the grown PtSix. The achieved nanowires are characterised by a low resistivity: 26 +/- 3 and 34 +/- 2 mu Omega cm for the Pt2Si- and PtSi-dominated nanowires.
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| 6. |
- Zhang, Zhen, et al.
(författare)
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Ni2Si nanowires of extraordinarily low resistivity
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:21, s. 213103-
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Tidskriftsartikel (refereegranskat)abstract
- Ultralong, polycrystalline Ni2Si nanowires are fabricated by combining sidewall transfer lithography with self-aligned silicidation. Upon formation at 500 degrees C, the nanowires that are 400 mu m long with a rectangular cross section of 37.5 by 25.3 nm are characterized by a resistivity of 25 +/- 1 mu Omega cm which is similar to the value for Ni2Si thin films. Further annealing at 800 degrees C results in an extraordinarily low wire resistivity of 10 mu Omega cm. Such a drastic decrease in resistivity is attributed to a significant grain growth and a low density of defects in the nanowires.
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| 7. |
- Zhang, Zhen, et al.
(författare)
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Performance fluctuation of FinFETs with Schottky barrier source/drain
- 2008
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 29:5, s. 506-508
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Tidskriftsartikel (refereegranskat)abstract
- A considerable performance fluctuation of FinFETs featuring PtSi-based Schottky barrier source/drain is found. The Fin-channels measure 27-nm tall and 35-nm wide. Investigation of similarly processed transistors of broad gate-widths reveals a large variation in the position of the PtSi/Si interface with reference to the gate edge along the gate width. This variation suggests an uneven underlap between the PtSi and the gate from device to device for the FinFETs, since essentially only one silicide grain would be in contact with each Fin-channel at the PtSi/Si interface. The size of the underlap is expected to sensitively affect the performance of the FinFETs.
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| 8. |
- Zhang, Zhen, et al.
(författare)
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Robust, scalable self-aligned platinum silicide process
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:14, s. 142114-
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Tidskriftsartikel (refereegranskat)abstract
- A robust, scalable PtSix process is developed. The process consists of two consecutive annealing steps in a single run; the first is silicidation of Pt films on Si substrates carried out in N-2, whereas the second is surface oxidation of the resultant PtSix in O-2. By adequately adjusting the temperature during the oxidation step, a protective SiOx hard mask forms on PtSix of different thicknesses and compositions. Such a surface oxidation is absent for Pt on SiO2 isolation, which is crucial for the subsequent selective wet etch for a self-aligned process. Ultralong PtSix nanowires are fabricated using this robust self-aligned process.
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