GeSn layers with enhanced photosensitivity by field effect

Project Director: Dr. Adrian SLAV
Project ID: 39PD from 02/05/2018 (PN-III-P1-1.1-PD-2016-1631)
Project Director: Dr. Adrian SLAV
Project Type: National Project Program PD
Funded by: Romanian National Authority for Scientific Research, UEFISCDI
Contractor: National Institute of Materials Physics
Project Status: In progress
Start Date: Wednesday, 2 May, 2018
End Date: Thursday, 30 October, 2020
Project Abstract:
The aim of this project is to obtain GexSn1-x by magnetron sputtering (MS) for field effect (FE) enhanced photo-sensing in extended near-infrared (NIR) range 1-3um. Sensitive detection of infrared (IR) light, especially in the mid- and far-infrared ranges, is extremely desirable in many important fields such as biology, astronomy, and medical science. The present IR photodetector market is dominated by III-V (InGaAs) alloys and chalcogenides (PbS, PbSe), materials of high toxicity and incompatible with silicon technology for integrated photonics. Therefore, it is important to develop new material technology based on ecologic materials as those of IV group elements, compatible with silicon technology for monolithic photonic integration. The advantage of alloying a semiconductor Ge with a semimetal Sn is the reduction of the bandgap, extending the NIR sensitivity of Ge, but also in obtaining a transition to direct bandgap IV-group semiconductors with higher optoelectronic properties. The project proposes the fabrication of GexSn1-x/oxide/Si-substrate structures. Sn concentration, layer thickness, deposition temperature, and post-annealing parameters will be varied for optimization of GexSn1-x films. Two type of structures will be grown by MS, nanostructured by rapid thermal annealing and characterized from point of view of structural, electrical and optical properties. The two types of structures refer to alternatives of using as gate oxide either thermally grown SiO2 or HfO2 deposited by MS. For obtaining a high spectral photoresponse, the Si substrate as a gate electrode will be employed. The unintentional doping due to local disorder (vacancies) in GeSn layers with negative consequences on photoconductivity properties is compensated by charges injected by FE, controlling the carrier density without creation of additional structural defects, changing the photo-carriers recombination and thus, improving the photoconduction properties of GeSn.
List of Publications:
  • "Epitaxial GeSn Obtained by High Power Impulse Magnetron Sputtering and the Heterojunction with Embedded GeSn Nanocrystals for Shortwave Infrared Detection", Ioana Dascalescu, Nicolae C. Zoita, Adrian Slav, Elena Matei, Sorina Iftimie, Florin Comanescu, Ana-Maria Lepadatu, Catalin Palade, Sorina Lazanu, Dan Buca, Valentin S. Teodorescu, Magdalena L. Ciurea, Mariana Braic, and Toma Stoica, ACS Applied Materials & Interfaces 2020 12 (30), 33879-33886DOI: 10.1021/acsami.0c06212
  • "Influence of SiGe Nanocrystallization on Short-Wave Infrared Sensitivity of SiGe-TiO2 Films and Multilayers", Ana-Maria Lepadatu, Catalin Palade, Adrian Slav, Ovidiu Cojocaru, Valentin-Adrian Maraloiu, Sorina Iftimie, Florin Comanescu, Adrian Dinescu, Valentin S. Teodorescu, Toma Stoica, Magdalena L. Ciurea, accepted manuscript to The Journal of Physical Chemistry (manuscript ID:jp-2020-06290f.R1), 15 October 2020
  • "GeSn/SiO2 multilayers by magnetron sputtering deposition for SWIR photonics", Adrian Slav, Ioana Dascalescu, Ana-Maria Lepadatu, Catalin Palade, Nicolae C. Zoita, Hermine Stroescu, Sorina Iftimie, Sorina Lazanu, Mariuca Gartner, Dan Buca, Valentin S.Teodorescu, Magdalena L. Ciurea, Mariana Braic, Toma Stoica, submitted to ACS Applied Materials & Interfaces (manuscript ID: am-2020-15887m)
Conference papers:
  • “GeSn nanocrystals in oxide matrix obtained by magnetron sputtering deposition”, A. Slav, M. Braic, C. Palade, A. Lepadatu, C Logofatu, S. Iftimie, S. Antohe, V.S. Teodorescu, M.L. Ciurea, T. Stoica,  “12th International Conference on Physics of Advanced Materials”, 21-28 September 2018,
    oral presentation,
  • ”GeSnSiO2 layers with embedded GeSn nanocrystals for sensing in SWIR”, A. Slav, C. Palade, C. Logofatu, I. Dascalescu, A.M. Lepadatu, I. Stavarache, S. Iftimie, V. Braic, S. Antohe, S. Lazanu, V. S. Teodorescu, D. Buca, M. L. Ciurea, T. Stoica, M. Braic, E-MRS Spring Meeting 2019, Symposium N -“Nanoengineered coatings and thin films:from design to application”, oral presentation;
  • Advances in Ge nanocrystals-based structures for SWIR sensors and non-volatile memories”, C. Palade, A. Slav, A.M. Lepadatu, I. Stavarache, I. Dascalescu, O. Cojocaru, I. Lalau, S. Lazanu, C. Logofatu, T. Stoica, V.S. Teodorescu, M.L. Ciurea, IBWAP 2019, 16-19 July 2019, Constanta, oral presentation;
  • Controlling SWIR photosensitivity limit by composition engineering: from Ge to GeSi nanocrystals embedded in TiO2, I. Dascalescu, O. Cojocaru, I. Lalau, C. Palade, A. Slav, A.M. Lepadatu, S. Lazanu, T. Stoica, M.L. Ciurea, IEEE CAS Conference Sinaia, Romania, October 9-11, 2019, Proc. CAS, IEEE Catalog Number: CFP19CAS-USB, ISBN: 978-1-7281-1887-1, p. 37-40, oral presentation;
  • “SWIR photoresponse of SiGe/TiO2 multilayers with Ge-rich SiGe nanocrystals”, A.M. Lepadatu, C. Palade, A. Slav, I. Dascalescu, O. Cojocaru, S. Iftimie, V.S. Teodorescu, T. Stoica, M.L. Ciurea, IEEE CAS Conference Sinaia, Romania, October 7-9, 2020, Proc. CAS, IEEE Catalog Number: CFP20CAS-USB, ISBN: 978-1-7281-1072-1, p. 235-238, oral presentation.


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