Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Group IV (other than C): Si/Ge/SiC

HL 39.3: Talk

Thursday, March 15, 2018, 11:30–11:45, EW 015

Crystal phase effects in group IV nanowire polytypes and their homojunctions — •Michele Amato — Laboratoire de Physique des Solides (LPS) Centre de Nanosciences et de Nanotechnologies (C2N) Université Paris-Sud, Orsay (France)

Recent experimental investigations have confirmed the possibility to synthesize and exploit polytypism in group IV nanowires. Indeed, while the crystal structure of Si and Ge nanowires (NWs) at standard conditions usually takes a well-defined cubic-diamond phase (as for their bulk counterparts), in the last few years several experimental observations of NWs exhibiting other phases - i.e. the hexagonal-diamond one - have been reported [1-2]. Driven by this promising evidence, here I will discuss recent first-principles calculations of the electronic and optical properties of hexagonal-diamond and cubic-diamond Si and Ge NWs as well as their homojunctions [3-4]. I will outline how a change in the crystal phase can strongly modify the electronic structure and optical response of the NW inducing novel and fascinating properties. Furthermore, I will show that, in the case of homojunctions, playing on crystal phase, size and length of the junction is an efficient tool to modulate band offsets and electron-hole separations.

References

[1] S. Assali et al., Nano Lett. 15, 8062-8069 (2015)

[2] J. Tang et al., Nanoscale, 9, 8113-8118 (2017)

[3] M. Amato et al., Nano Lett. 16, 5694-5700 (2016)

[4] T. Kaewmaraya et al., J. Phys. Chem. C 121, 5820-5828 (2017)