Structural and luminescence imaging and characterisation of semiconductors in the scanning electron microscope

Trager-Cowan, Carol and Alasmari, Aeshah and Avis, William and Bruckbauer, Jochen and Edwards, Paul R and Ferenczi, Gergely and Hourahine, Benjamin and Kotzai, Almpes and Kraeusel, Simon and Kusch, Gunnar and Martin, Robert W and McDermott, Ryan and Gunasekar, Naresh and Nouf-Allehiani, M. and Pascal, Elena and Thomson, David and Vespucci, Stefano and Smith, Matthew David and Parbrook, Peter J and Enslin, Johannes and Mehnke, Frank and Kuhn, Christian and Wernicke, Tim and Kneissl, Michael and Hagedorn, Sylvia and Knauer, Arne and Walde, Sebastian and Weyers, Markus and Coulon, Pierre-Marie and Shields, Philip and Bai, J. and Gong, Y. and Jiu, Ling and Zhang, Y. and Smith, Richard and Wang, Tao and Winkelmann, Aimo (2020) Structural and luminescence imaging and characterisation of semiconductors in the scanning electron microscope. Semiconductor Science and Technology, 35 (5). 054001. ISSN 0268-1242

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    Abstract

    The scanning electron microscopy techniques of electron backscatter diffraction (EBSD), electron channelling contrast imaging (ECCI) and cathodoluminescence (CL) hyperspectral imaging provide complementary information on the structural and luminescence properties of materials rapidly and non-destructively, with a spatial resolution of tens of nanometres. EBSD provides crystal orientation, crystal phase and strain analysis, whilst ECCI is used to determine the planar distribution of extended defects over a large area of a given sample. CL reveals the influence of crystal structure, composition and strain on intrinsic luminescence and/or reveals defect-related luminescence. Dark features are also observed in CL images where carrier recombination at defects is non-radiative. The combination of these techniques is a powerful approach to clarifying the role of crystallography and extended defects on a material's light emission properties. Here we describe the EBSD, ECCI and CL techniques and illustrate their use for investigating the structural and light emitting properties of UV-emitting nitride semiconductor structures. We discuss our investigations of the type, density and distribution of defects in GaN, AlN and AlGaN thin films and also discuss the determination of the polarity of GaN nanowires.