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CVD growth of GeSnSiC alloys using disilane, digermane, tin tetrachloride and methylsilane
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
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2014 (English)In: ECS Transactions, 2014, Vol. 64, no 6, 703-710 p.Conference paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
2014. Vol. 64, no 6, 703-710 p.
, ECS Transactions, ISSN 1938-5862 ; 6
Keyword [en]
Epitaxial growth, Germanium, Oxygen, Quality control, Rapid thermal annealing, Silicon, Silicon alloys, Thermodynamic stability, Tin, Boron and carbons, Compressive strain, Device fabrications, Epitaxial quality, Growth parameters, Integration issues, Layer thickness, Rapid thermal annealing (RTA), Tensile strain
National Category
Materials Engineering Materials Chemistry
URN: urn:nbn:se:kth:diva-167544DOI: 10.1149/06406.0703ecstScopusID: 2-s2.0-84921269093OAI: diva2:818911
6th SiGe, Ge, and Related Compounds: Materials, Processing and Devices Symposium - 2014 ECS and SMEQ Joint International Meeting, 5 October 2014 through 9 October 2014

QC 20150609

Available from: 2015-06-09 Created: 2015-05-22 Last updated: 2016-09-06Bibliographically approved
In thesis
1. Growth, processing and characterization of group IV materials for thermoelectric applications
Open this publication in new window or tab >>Growth, processing and characterization of group IV materials for thermoelectric applications
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Discover of new energy sources and solutions are one of the important global issues nowadays, which has a big impact on economy as well as environment. One of the methods to help to mitigate this issue is to recover wasted heat, which is produced in large quantities by the industry, through vehicle exhausts and in many other situations where we consume energy. One way to do this would be using thermoelectric (TE) materials, which enable direct interconversion between heat and electrical energy. This thesis investigates how the novel material combinations and nanotechnology could be used for fabricating more efficient TE materials and devices.

The work presents synthesis, processing, and electrical characterization of group IV materials for TE applications. The starting point is epitaxial growth of alloys of group IV elements, silicon (Si), germanium (Ge) and tin (Sn), with a focus on SiGe and GeSn(Si) alloys. The material development is performed using chemical vapor deposition (CVD) technique. Strained and strain-relaxed Ge1-x Snx (0.01≤x≤0.15) has been successfully grown on Ge buffer and Si substrate, respectively. It is demonstrated that a precise control of temperature, growth rate, Sn flow and buffer layer quality is necessary to overcome Sn segregation and achieve a high quality GeSn layer. The incorporation of Si and n- and p-type dopant atoms is also investigated and it was found that the strain can be compensated in the presence of Si and dopant atoms. 

Si1-xGexlayers are grown on Si-on-insulator wafers and condensed by oxidation at 1050 ᵒC to manufacture SiGe-on-insulator (SGOI) wafers. Nanowires (NWs) are processed, either by sidewall transfer lithography (STL), or by using conventional lithography, and subsequently manufactured into nanoscale dimensions by focused ion beam (FIB) technique. The NWs are formed in an array, where one side is heated by a resistive heater made of Ti/Pt. The power factor of NWs is measured and the results are compared for NWs manufactured by different methods. It is found that the electrical properties of NWs fabricated with FIB technique can be influenced due to Ga doping during ion milling.

Finally, the carrier transport in SiGe NWs formed on SGOI samples is tailored by applying a back-gate voltage on the Si substrate. In this way, the power factor is improved by a factor of 4. This improvement is related to the presence of defects and/or small fluctuation of nanowire shape and Ge content along the NWs, generated during processing and condensation of SiGe layers. The SiGe results open a new window for operation of SiGe NWs-based TE devices in the new temperature range of 250 to 450 K.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 53 p.
TRITA-ICT, 2016:20
Thermoelectric, SiGe, GeSn(Si), Chemical vapor deposition, Nanowires
National Category
Nano Technology Other Physics Topics
Research subject
urn:nbn:se:kth:diva-192142 (URN)978-91-7729-076-6 (ISBN)
External cooperation:
Public defence
2016-09-30, Sal B, Kistagången 16, Kista, 10:00 (English)
Swedish Foundation for Strategic Research , EM11-0002

QC 20160907

Available from: 2016-09-07 Created: 2016-09-06 Last updated: 2016-09-09Bibliographically approved

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Noroozi, MohammadAbedin, AhmadMoeen, MahdiÖstling, MikaelRadamson, Henry H.
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