Speaker
Description
The combination of core-shell geometry and band gap engineering in nanowire (NW) heterostructures can be employed to realize systems with novel transport and optical properties. The InAs/GaSb material system is particularly interesting because of the very low lattice-mismatch (0.6%), broken-gap band alignment (type-III), and small effective masses of electrons and holes in InAs and GaSb regions, respectively. Electronic devices fabricated with these heterostructures can display negative differential resistance due to transport across the broken gap junction. Further interesting Coulomb interaction can be achieved if carriers in the two closely spaced channels are decoupled. To this end, here we report the growth of catalyst-free InAs/InP/GaAsSb core-dual-shell (CDS) NWs by chemical beam epitaxy. Detailed morphological, structural, strain and compositional studies of the NWs as a function of growth parameters have been performed. We found that the InP shell facets are well developed along the crystallographic <110> and <112> directions only when the nominal thickness is above 1 nm. Furthermore, both InP and GaAsSb shells grow almost coherently to the InAs core along the <112> direction and elastically compressed along the <110> direction [1]. Finally, we have used the optimized CDS NWs to fabricate two and four terminal field effect transistor devices. Thanks to the four-terminal device architecture, in the same NW we could independently measure charge transport along the outer GaAsSb shell, the inner InAs core, and across the radial heterojunction enabling us to investigate the absence of tunnel-ling current between the n-type core and the p-type shell and the impact of ultrathin InP barrier. The results demonstrated that a 10 nm thick InP barrier effectively quenches the tunneling between the InAs core and outer GaAsSb shell [2].
References:
[1] O. Arif, et al., Cryst. Growth Des. 20, 1088-1096 (2020).
[2] S. Salimian, et al., Nano Res. 13, 1065-1070 (2020).
| Speaker Country | Italy |
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