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| 3. |
- Hu, Cheng, et al.
(författare)
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Characterization of Ni(Si,Ge) films on epitaxial SiGe(100) formed by microwave annealing
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:9, s. 092101-
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Tidskriftsartikel (refereegranskat)abstract
- Microwave annealing (MWA) is investigated as an alternative technique to rapid thermal processing with halogen lamp heating (RTP) for low-temperature silicide formation on epitaxially grown Si0.81Ge0.19 layers. Phase formation, resistivity mapping, morphology analysis, and composition evaluation indicate that the formation of low-resistivity NiSi1-xGex by means of MWA occurs at temperatures about 100 degrees C lower than by RTP. Under similar annealing conditions, more severe strain relaxation and defect generation are therefore found in the remaining Si0.81Ge0.19 layers treated by MWA. Although silicidation by microwave heating is in essence also due to thermal effects, details in heating mechanisms differ from RTP.
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| 4. |
- Jamshidi, Asghar, et al.
(författare)
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Growth of GeSnSiC layers for photonic applications
- 2013
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 230, s. 106-110
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Tidskriftsartikel (refereegranskat)abstract
- This work presents epitaxial growth of intrinsic and doped GeSnSiC layers using Ge2H6, SnCl4, CH3SiH3, B2H6, PH3 and Si2H6 deposited at 290-380 degrees C on strain relaxed Ge buffer layer or Si substrate by using reduced pressure chemical vapor deposition (RPCVD) technique. The GeSnSi layers were compressively strained on Ge buffer layer and strain relaxed on Si substrate. It was demonstrated that the quality of epitaxial layers is dependent on the growth parameters and that the Sn content in epi-layers could be tailored by growth temperature. The Sn segregation caused surface roughness which was decreased by introducing Si and Si-C into Ge layer. less thanbrgreater than less thanbrgreater thanThe Sn content in GeSn was carefully determined from the mismatch, both parallel and perpendicular, to the growth direction when the Poisson ratio was calculated for a certain Ge-Sn composition. The X-ray results were excellently consistent with Rutherford Backscattered Spectroscopy (RBS). Strain relaxed GeSn layers were also used as virtual substrate to grow tensile-strained Ge layers. The Ge cap layer had low defect density and smooth surface which makes it a viable candidate material for future photonic applications.
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| 5. |
- Noroozi, Mohammad, et al.
(författare)
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CVD growth of GeSnSiC alloys using disilane, digermane, tin tetrachloride and methylsilane
- 2014
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-6737. ; , s. 703-710
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Konferensbidrag (refereegranskat)abstract
- In this study, Ge1-x-y-zSnxSiyCz layers (0.01≤x≤ 0.06, 0≤y≤0.02 and 0≤z≤0.01) have been successfully grown at 280-330 °C on Ge and Si by using RPCVD technique. It was demonstrated that the quality of epitaxial layers is dependent on the growth parameters, layer thickness and the quality of Ge virtual layer. It was found that a proper strain balance in the matrix during the epitaxy where the Si is adjusted carefully with the Sn flux improves the incorporation of Sn in Ge matrix. A similar improvement of Sn incorporation has been observed for phosphorous, boron and carbon doping in GeSn layers as well. This is explained by the compensation of the compressive strain caused by Snand the tensile strain induced by Si to obtain the minimum energy in Ge matrix. This behavior was not observed for relaxed GeSn layers and Sn incorporation could be controlled only by the growth parameters. The thermal stability of GeSn is an important integration issue for device fabrication. The thermal stability of P- and B-doped GeSn layers was studied by rapid thermal annealing (RTA) in range of 400-600 °C and compared with intrinsic layers. The GeSn layers were stable up to 550 °C while the B-doped layers showed strain relaxation readily at 500 °C. The epitaxial quality of epi-layers was evaluated in terms of oxygen and water vapor contamination. The level of oxygen during epitaxy was as low as 10 ppb and the contamination amount was found as low as 1017 cm-3.
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| 6. |
- Noroozi, Mohammad, et al.
(författare)
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Effect of strain on Ni-(GeSn)x contact formation to GeSn nanowires
- 2014
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Ingår i: Materials Research Society Symposium Proceedings. - : Springer Science and Business Media LLC.
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Konferensbidrag (refereegranskat)abstract
- In this study, the formation of Ni-(GeSn)x on strained and relaxed Ge1-xSnx (0.01≤x≤ 0.03) nanowires in contact areas has been investigated. The epi-layers were grown at different temperatures (290 to 380°C) by RPCVD technique. The strain in GeSn layers tailored through carefully chosen of growth parameters and virtual substrate. The nanowires were fabricated through both I-line and dry-etching. 15 nm Ni was deposited either on the contact areas or whole length of nanowires. The wires went through rapid thermal annealing at intervals of 360 to 550°C for 30s in N2 ambient. The results show the thermal stability and amount of particular phases were strain-dependent. The formation of Ni-GeSn was eased when GeSn layers were strain-free. When the Sn content is high the epi-layers suffer from Sn segregation. The Sn-rich surface impedes remarkably the Ni diffusion. The electrical conductivity measurement of nanowires shows low resistivity and Ohmic contact are obtained for Ni-GeSn.
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| 7. |
- Noroozi, Mohammad, et al.
(författare)
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Fabrication and thermoelectric characterization of GeSn nanowires
- 2014
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Ingår i: 2014 15th International Conference on Ultimate Integration on Silicon, ULIS 2014. - : IEEE Computer Society. - 9781479937189 ; , s. 125-128
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Konferensbidrag (refereegranskat)abstract
- In this study, GeSn nanowires (NWs) were fabricated and the thermoelectric performance in terms of power factor and contact resistance have been investigated and compared to Ge and Si. The ohmic contact to the NWs was made by Pt/Ti whereas low contact resistance was obtained by Ni-GeSn (or Ni-Ge) layers. A detailed investigation was performed to process towards low resistance Ni-GeSn phase for GeSn NWs. The phase formation of Ni-GeSn layers was examined by x-ray diffraction (XRD) and the residual strain in GeSn beneath the Ni-GeSn was also measured by high resolution reciprocal lattice mapping (HRRLM). It was demonstrated that Ni reaction with GeSn layer resulted in strain reduction in the remained GeSn material due to Ni outdiffusion to the GeSn NWs demonstrated higher Seebeck coefficient compared to Ge and Si NWs, which suggest promising thermoelectric properties in GeSn.
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| 8. |
- Noroozi, Mohammad, et al.
(författare)
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Fabrications of size-controlled SiGe nanowires using I-line lithography and focused ion beam technique
- 2014
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; , s. 167-174
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Konferensbidrag (refereegranskat)abstract
- In this study, a novel method using Focus Ion Beam (FIB) technique was applied to scale down Si1-xGex wires (x=0.27-0.57) to 20 nm width. Originally, the wires were processed by using Iline lithography and dry etching of SiGe on oxide (SGOI) substrates. The SGOI wafers were processed through condensation method where a SiGe/Si layer was grown in the beginning on SOI wafers and oxidized at 850-1050 °C. The shape of the nanowires (NWs) during the successive FIB cutting was examined by scanning electron microscopy (SEM) and the carrier transport through the NWs was checked by resistivity measurements. The contact resistance was reduced by Ni-silicide prior to metallization. The fabricated NWs were also suspended by tilting FIB. The results present the limitations and challenges of FIB technique to create NWs for advanced sensors and transistors.
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| 9. |
- Noroozi, Neda, et al.
(författare)
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Decomposability in Input Output Conformance Testing
- 2013
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Ingår i: Proceedings of the 8th Workshop on Model-Based Testing. - : Open Publishing Association. ; , s. 51-66
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Konferensbidrag (refereegranskat)abstract
- We study the problem of deriving a specification for a third-party component, based on the specifi-cation of the system and the environment in which the component is supposed to reside. Particularly,we are interested in using component specifications for conformance testing of black-box components, using the theory of input-output conformance (ioco) testing. We propose and prove sufficientcriteria for decompositionality, i.e., that components conforming to the derived specification will always compose to produce a correct system with respect to the system specification. We also study thecriteria for strong decomposability, by which we can ensure that only those components conformingto the derived specification can lead to a correct system.
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| 10. |
- Noroozi, Neda, et al.
(författare)
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On the Complexity of Input Output Conformance Testing
- 2014
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Ingår i: Formal Aspects of Component Software. - Heidelberg : Springer. - 9783319076010 - 9783319076027 ; , s. 291-309
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Konferensbidrag (refereegranskat)abstract
- Input-output conformance (ioco) testing is a well-known approach to model-based testing. In this paper, we study the complexity of checking ioco. We show that the problem of checking ioco is PSPACE-complete. To provide a more efficient algorithm, we propose a more restricted setting for checking ioco, namely with deterministic models and show that in this restricted setting ioco checking can be performed in polynomial time. © 2014 Springer International Publishing Switzerland.
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| 11. |
- Noroozi, Neda, et al.
(författare)
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Synchronizing Asynchronous Conformance Testing
- 2011
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Ingår i: Proceedings of the 9th International Conference on Software Engineering and Formal Methods (SEFM 2011). - Berlin : Springer Berlin/Heidelberg. - 9783642246890 ; , s. 334-349
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Konferensbidrag (refereegranskat)abstract
- We present several theorems and their proofs which enable using synchronous testing techniques such as input output conformance testing (ioco ) in order to test implementations only accessible through asynchronous communication channels. These theorems define when the synchronous test-cases are sufficient for checking all aspects of conformance that are observable by asynchronous interaction with the implementation under test. © 2011 Springer-Verlag.
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| 12. |
- Radamson, Henry H., et al.
(författare)
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Strain engineering in GeSnSi materials
- 2012
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Ingår i: SiGe, Ge, and related compounds 5. - : Electrochemical Society. - 9781607683575 ; , s. 527-531
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Konferensbidrag (refereegranskat)abstract
- In this study, Ge1-x-ySnxSiy layers (0.01≤x≤ 0.06 and 0≤y≤0.12) using Ge2H6, SnCl4 (SnD4) and Si2H6 have successfully grown at 290-310 °C on Ge virtual layer on Si(100) by using RPCVD technique. It has been demonstrated that the quality of epitaxial layers is dependent on the growth parameters, layer thickness and the quality of Ge virtual layer. The incorporation of P and B in GeSn matrix has been studied and the effect of dopant specie and concentration on Sn content has been presented. It was found that a proper balance of P, B or Si and Sn flux during the epitaxy improves the incorporation of Sn in Ge matrix. This is explained by the compensation of tensile strain induced by dopants or Si with the compressive strain caused by Sn to obtain the minimum energy in Ge matrix. P-i-n type doped structures of Ge-Sn-Si were grown and the layer quality was analyzed.
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