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Author Gkanatsiou, A.; Lioutas, C.B.; Frangis, N.; Polychroniadis, E.K.; Prystawko, P.; Leszczynski, M.; Altantzis, T.; Van Tendeloo, G. url  doi
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  Title Influence of 4H-SiC substrate miscut on the epitaxy and microstructure of AlGaN/GaN heterostructures Type A1 Journal article
  Year (down) 2019 Publication Materials science in semiconductor processing Abbreviated Journal Mat Sci Semicon Proc  
  Volume 91 Issue Pages 159-166  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract AlGaN/GaN heterostructures were grown on “on-axis” and 2° off (0001) 4H-SiC substrates by metalorganic vapor phase epitaxy (MOVPE). Structural characterization was performed by transmission electron microscopy. The dislocation density, being greater in the on-axis case, is gradually reduced in the GaN layer and is forming

dislocation loops in the lower region. Steps aligned along [11̅00] in the off-axis case give rise to simultaneous defect formation. In the on-axis case, an almost zero density of steps is observed, with the main origin of defects probably being the orientation mismatch at the grain boundaries between the small not fully coalesced AlN grains. V-shaped formations are observed in the AlN nucleation layer, but are more frequent in the off-axis case, probably enhanced by the presence of steps. These V-shaped formations are completely overgrown by the GaN layer, during the subsequent deposition, presenting AlGaN areas in the walls of the defect, indicating an interdiffusion between the layers. Finally, at the AlGaN/GaN heterostructure surface in the on-axis case, V-shapes are observed, with the AlN spacer and AlGaN (21% Al) thickness on relaxed GaN exceeding the critical thickness for relaxation. On the other hand, no relaxation in the form of V-shape creation is observed in the off-axis case, probably due to the smaller AlGaN thickness (less than 21% Al). The AlN spacer layer, grown in between the heterostructure, presents a uniform thickness and clear interfaces.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000454537700022 Publication Date 2018-11-26  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1369-8001 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 2.359 Times cited 1 Open Access Not_Open_Access  
  Notes Funding: This work was supported by the IKY Fellowships of Excellence for Postgraduate Studies in Greece-SIEMENS Program; the Greek General Secretariat for Research and Technology, contract SAE 013/8–2009SE 01380012; and the JU ENIAC Project LAST POWER Large Area silicon carbide Substrates and heteroepitaxial GaN for POWER device applications [grant number 120218]. Also part of the research leading to these results has received funding from the European Union Seventh Framework Program under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative–I3). T.A. acknowledges financial support from the Research Foundation Flanders (FWO, Belgium) through a post-doctoral grant. Approved Most recent IF: 2.359  
  Call Number EMAT @ emat @UA @ admin @ c:irua:156200 Serial 5149  
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Author Lioutas, C.B.; Manolikas, C.; Van Tendeloo, G.; van Landuyt, J. pdf  doi
openurl 
  Title A 2a2a3c superstructure in hexagonal Ni1-xS : a study by means of electron-diffraction and HRTEM Type A1 Journal article
  Year (down) 1993 Publication Journal of crystal growth Abbreviated Journal J Cryst Growth  
  Volume 126 Issue 2-3 Pages 457-465  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract The high temperature phase of Ni1-xS has the NiAs-type structure. The coexistence of two superstructures, ''3a3a3c'' and ''2a2a3c'' with the basic phase is confirmed by means of electron diffraction. The 2a2a3c superstructure is studied by means of electron diffraction and high resolution electron microscopy. A structure model is proposed based on the periodic insertion of stacking faults in the NiAs-type basic structure and the ordering of vacancies in alternate metal-atom layers. Microtwinning in very narrow slabs is found to be a main feature of the 2a2a3c regions and two defect models are discussed.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Amsterdam Editor  
  Language Wos A1993KH92500029 Publication Date 2002-10-16  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-0248; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 1.698 Times cited 4 Open Access  
  Notes Approved no  
  Call Number UA @ lucian @ c:irua:103012 Serial 23  
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Author Lioutas, C.B.; Manolikas, C.; Van Tendeloo, G.; van Landuyt, J. openurl 
  Title A 2a2b3c superstructure in hexagonal NiS1-x: a study by means of electron diffraction and HREM Type A1 Journal article
  Year (down) 1993 Publication Journal of crystal growth Abbreviated Journal J Cryst Growth  
  Volume 126 Issue Pages 457-465  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Amsterdam Editor  
  Language Wos A1993KH92500029 Publication Date 0000-00-00  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-0248 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 1.698 Times cited 4 Open Access  
  Notes Approved no  
  Call Number UA @ lucian @ c:irua:7499 Serial 9  
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