Invited Paper EM+2D+AP+NS+PS-TuM10
Combining 2D and 1D Atomic Scale Tailored Nanowire Surfaces for Novel Electronics and Photonics

Tuesday, October 22, 2019, 11:00 am, Room A214

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 have 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 use these methods for studying atomic scale crystal phase changes, the impact on local electronic properties and demonstrating full 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 1D and 2D compositional control at the monolayer level. Further we show how Bi can form unique 1D and 2D structures in particular on the unique Wz GaAs NW segments. 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 lattice change [6], which is effectively a small 2D material segment in a 1D structure. We find that the general Zb electronic structure is preserved locally in even the smallest segments and signatures of confined states in them.

Characterization to the atomic scale during electrical and optical operation is necesarry to understand and develop the functionality of structures as discussed above. 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 1D Wz and Zb crystal phases down to a few femtoseconds temporally and a few tens of nanometer spatially[8].

[1] E. Hilner et al., Nano Lett., 8 (2008) 3978; M. Hjort et al., ACS Nano 6 (2012) 9679

[2] M. Hjort et al., Nano Lett., 13 (2013) 4492; M. Hjort et al., ACS Nano, 8 (2014) 12346

[3] J.L. Webb, et al Nano Lett. 15 (2015) 4865

[4] O. Persson et al., Nano Lett. 15 (2015) 3684

[5] M. Hjort et al Nano Lett., 17 (2017) 3634

[6] J.V. Knutsson e tal ACS Nano, 11 (2017) 10519

[7] J.L. Webb et al, Sci. Rep. 7 (2017) 12790

[8] E. Mårsell et al, Nano Lett. 18 (2018) 907