Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2
by Lionel C Gontard, Jörg R Jinschek, Haiyan Ou, Jo Verbeeck and Rafal E Dunin-Borkowski
A scanning transmission electron microscope is a versatile instrument, which can be used to illuminate a thin specimen with a focused beam of electrons to detect the scattered electron intensity to form an image. Besides providing useful information about the specimen, the electron beam can also be used to cause either temporary or permanent changes to its surface or bulk structure. The incident electron beam can result in defect formation, mass loss, atom displacement, phase transitions, a change in temperature, and the presence of an electric field, arising both from the electron beam itself and from charging of the specimen.
In the present study, the local transformations that are induced in a sample that is being irradiated selectively have been investigated in three dimensions making use of high spatial resolution HAADF STEM tomography by adjusting the dwell time to avoid further damage to the material during subsequent imaging. By this means the electron beam in an electron microscope can be used to create regular arrays of core-shell cylinders with well-defined diameters and pitches.
In some of the core-shell structures, a coaxial-like structure is observed. These structures can have the topology of photonic crystals on the nanometre scale and may be important for tailor-made electronic and/or optical devices such as plasmonic sensors or transistors. They are also playgrounds for studying physics in quasi-one-dimensional systems but are also important for technological and scientific applications in which insulating materials are irradiated with highly energetic charged particles. For example, proton beams are used in the treatment of human cells, insulating materials are used as protective layers in fusion and fission reactors, and semiconductors are routinely used for detecting particles in high-energy physics.
Lionel C Gontard, Jörg R Jinschek, Haiyan Ou, Jo Verbeeck and Rafal E Dunin-Borkowski: Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2, Applied Physics Letters 100 (2012) 263113.