semiconductor nanowire; doping; one-dimensional structure; nanowire-based heterostructures
Yang Z., Surrente A., Tutuncuoglu G., Galkowski K., Cazaban-Carrazé M., Amaduzzi F., Leroux P., Maude D. K., Fontcuberta i Morral A., Plochocka P. (2017), Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes, in Nano Letters
, 17(5), 2979-2984.
Boland Jessica L., Casadei Alberto, Tütüncüoglu Gözde, Matteini Federico, Davies Christopher L., Jabeen Fauzia, Joyce Hannah J., Herz Laura M., Fontcuberta i Morral Anna, Johnston Michael B. (2016), Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping, in ACS Nano
, 10(4), 4219-4227.
Amaduzzi Francesca, Alarcón-Lladó Esther, Hautmann Hubert, Tanta Rawa, Matteini Federico, Tütüncüoǧlu Gözde, Vosch Tom, Nygård Jesper, Jespersen Thomas, Uccelli Emanuele, Fontcuberta i Morral Anna (2016), Tuning the response of non-allowed Raman modes in GaAs nanowires, in Journal of Physics D: Applied Physics
, 49(9), 095103-095103.
Potts Heidi, Friedl Martin, Amaduzzi Francesca, Tang Kechao, Tuetuencueoglu Goezde, Matteini Federico, Llado Esther Alarcon, McIntyre Paul C., Fontcuberta i Morral Anna (2016), From Twinning to Pure Zincblende Catalyst-Free InAs(Sb) Nanowires, in NANO LETTERS
, 16(1), 637-643.
Ramezani Mohammad, Casadei Alberto, Grzela Grzegorz, Matteini Federico, Tütüncüoglu Gözde, Rüffer Daniel, Fontcuberta i Morral Anna, Gómez Rivas Jaime (2015), Hybrid Semiconductor Nanowire–Metallic Yagi-Uda Antennas, in Nano Letters
, 15(8), 4889-4895.
Boland Jessica L., Conesa-Boj Sonia, Parkinson Patrick, Tuetuencueoglu Goezde, Matteini Federico, Rueffer Daniel, Casadei Alberto, Amaduzzi Francesca, Jabeen Fauzia, Davies Christopher L., Joyce Hannah J., Herz Laura M., Fontcuberta i Morral Anna, Johnston Michael B. (2015), Modulation Doping of GaAs/AlGaAs Core-Shell Nanowires With Effective Defect Passivation and High Electron Mobility, in NANO LETTERS
, (2), 1336-1342.
Semiconductor nanowires are high aspect-ratio filamentary crystals with a tailored diameter in the sub-micron range. Thanks to their special geometry and dimensions, they hold great promise as building blocks for next generations of electronic and optoelectronic devices. Many of these applications have been only possible thanks to the introduction of impurities (doping) for the engineering of the electrical properties. In the last few years we have gained significant understanding on the incorporation of dopants in GaAs semiconductor nanowires. We understand now how Si, C and Be are incorporated in both the nanowire core and shell. We understand how n and p-type conductivity can be achieved, as well as different ranges of dopant concentrations. This understanding has allowed us to fabricate for example high quality pn junctions, which are now considered for next generation solar cells. The detailed understanding of doping in nanowires enables us to move further to the detailed study of more sophisticated structures which should also exhibit highly improved properties. In particular, we plan to reduce the size of the conducting channels and embed them within the nanowire structure. We will separate the nanoscale conducting channels from the surface and the dopants. Thereby we avoid the major sources of carrier scattering in nanowires. With this strategy we expect to increase the overall mobility of carriers in the nanowires. At the same time, thanks to the precise control of the nanowire heterostructures achieved by the use of molecular beam epitaxy (MBE), we expect to be able to tune the density of carriers to a much wider range than in ‘bulk’ doping. For this, it will be very important to understand if the nanowire geometry with its increased surface-to-volume ratio also implies a higher incorporation of unintentional dopants. We want to answer the main following questions:•What is the origin and location of residual doping in III-V nanowires fabricated by MBE? To what extend does residual doping change the functional properties of the heterostructures?•What limits the maximum carrier mobility in nanowires? Does it depend on the geometry or in the nature of surfaces/interfaces? •Does nanowire-based heterostructure design enable a wider range for the dopant concentrations compared to ‘bulk’ values? What is the effect of the distances between the delta-doping layer, the external surface and the conducting channel?The project is organized around the following aspects: the synthesis and the investigation of the electronic transport properties. The electronic transport properties will be investigated by performing magnetotransport experiments on contacted samples. We will also use alternative techniques and avoid electrical contacts that might provoke spurious effects. These techniques are Raman Spectroscopy (resonant and non-resonant), Photoluminescence (with and without the application of a magnetic field), optical-pump THz-probe spectroscopy and cantilever magnetometry at cryogenic temperatures. At the end of this project we hope to provide a fundamental understanding on the possibilities of doped nanowire-based heterostructures and the optimization of the electronic properties. We expect our results will be of general interest for a broad regime of nanowire-based applications and offer new perspectives for research on one-dimensional structures, e.g, quantum transport phenomena.