Anton Pishchagin
Growth of advanced functional heterostructures in III-V nanowires.
CNRS C2N
Semiconductor nanowires, with diameters of a few tens of nanometers and lengths up to several microns, are nowadays commonly fabricated from a large range of semiconductor materials. The remarkable physical properties of these objects open large prospects of original applications. However, their full potential will only be achieved if their physical properties can be precisely tailored. In addition to controlling the geometry, crystal structure and doping of the nanowires, two requirements are essential for most applications: (1) to obtain regular arrays of identical nanowires; (2) to confer novel functionalities to each nanowire by modulating locally its properties. The ultimate aim of the project is to combine these two objectives in the fabrication of arrays of nanowires including advanced functional heterostructures. To this end, I will perform research on the growth by molecular beam epitaxy (MBE) of nanowires of III-V semiconductors.
Specifically, I will explore the growth of two kinds of heterostructures. The first one involves a high aspect ratio quantum size insertion of a material different from the rest of the nanowire. The second one consists in a homogeneous nanowire where the spatial modulation of the electronic properties will be achieved not by varying the composition but the diameter of the structure. I will then aim at fabricating arrays of such structures on a patterned substrate with a high yield of vertical and identical nanowires.
An important aspect of the project is to maintain an intimate coupling between experimental investigations and modeling of the nucleation and growth mechanisms, which is a strength of the C2N team. I will thus attempt jointly to develop and perform advanced modeling of the growth of these structures and to investigate experimentally their fabrication.
Left: TEM image of a self-catalyzed GaP nanowire with thin GaAs insertions. Right: High resolution TEM image of a Ga(P,As) insertion in a GaP nanowire, with measurement of the variations of the phosphorus concentration across the insertion.
From Priante et al., Nano Lett. 15, 6036 (2015); work carried out at C2N (formerly CNRS-LPN) within the NanoEmbrace Marie Skłodowska-Curie project.
