Proceedings of nanoGe Fall Meeting 2018 (NFM18)
DOI: https://doi.org/10.29363/nanoge.nfm.2018.168
Publication date: 6th July 2018
The III-V nanowire (NW) technology platform has reached a level of advancement that allows atomic scale control of crystal structure and surface morphology as well as flexible device integration. In particular, controlled axial stacking of Wurtzite(Wz) and Zincblende(Zb) crystal phases is uniquely possible in the NWs. We explore how this can be used to affect electronic, optical and surface chemistry with atomic scale precision opening up for 1D, 2D and 3D structures with designed local properties.
We previously demonstrated atomically resolved Scanning Tunneling Microscopy/Spectroscopy (STM/S) on a wide variety of these III-V NWs and on operational NW devices[1-4]. We now study atomic scale crystal phase changes, their impact on local electronic properties and demonstrating atomic resolution STM during device operation[5-7]. We explore the surface alloying of Sb into GaAs NWs with controlled axial stacking of Wz and Zb crystal phases[5] demonstrating a simple processing-free route to compositional control at the monolayer level. Using 5K STM/S we measure local density of states of Zb crystal segments in Wz InAs NWs down to the smallest possible atomic scale crystal change[6]. The general Zb electronic structure is preserved locally in even the smallest possible segments and signatures of confined states are found. We demonstrate a novel device platform allowing STM/S with atomic scale resolution across a III-V NW device simultaneously with full electrical operation and high temperature processing in reactive gases[7].
Using 5-15 femtosecond laser pulses combined with PhotoEmission Electron Microscopy (PEEM) we explore local dynamic response of carriers in the Wz and Zb crystal phases down to a few femtoseconds temporally and a few tens of nanometer spatially. We demonstrate that spatial control of multiphoton electron excitations is possible in semiconductor NWs by changing the crystal phase, orientation, and light polarization[8]. The control and understanding of multiphoton excitations could be used in the design of optoelectronic components that use hot electrons or photoelectrons for functionality.
[1] E. Hilner etal., Nano Lett., 8 (2008) 3978; M. Hjort et al., ACS Nano 6 (2012) 9679
[2] M. Hjort etal., Nano Lett., 13 (2013) 4492; M. Hjort et al., ACS Nano, 8 (2014) 12346
[3] J.L. Webb, etal Nano Lett. 15 (2015) 4865
[4] O. Persson etal., Nano Lett. 15 (2015) 3684
[5] M. Hjort etal Nano Lett., 17 (2017) 3634
[6] J.V. Knutsson etal ACS Nano, 11 (2017) 10519
[7] J.L. Webb etal, Sci. Rep. 7 (2017) 12790
[8] E. Mårsell etal, Nano Lett. 18 (2018) 907
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