Hole and Electron Effective Masses in Single InP Nanowires with a Wurtzite-Zincblende Homojunction

Davide Tedeschi; H Aruni Fonseka; Elena Blundo; Andrés Granados Del Águila; Yanan Guo; Hark H Tan; Peter C M Christianen; Chennupati Jagadish; Antonio Polimeni; Marta De Luca

doi:10.1021/acsnano.0c04174

Hole and Electron Effective Masses in Single InP Nanowires with a Wurtzite-Zincblende Homojunction

ACS Nano. 2020 Sep 22;14(9):11613-11622. doi: 10.1021/acsnano.0c04174. Epub 2020 Sep 9.

Authors

Davide Tedeschi¹, H Aruni Fonseka^{2

3}, Elena Blundo¹, Andrés Granados Del Águila⁴, Yanan Guo², Hark H Tan^{2

5}, Peter C M Christianen⁶, Chennupati Jagadish^{2

5}, Antonio Polimeni¹, Marta De Luca⁷

Affiliations

¹ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy.
² Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
³ Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
⁴ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
⁵ ARC Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
⁶ High Field Magnet Laboratory (HFML - EMFL), Radboud University, Toernooiveld 7, NL-6525 ED Nijmegen, The Netherlands.
⁷ Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.

PMID: 32865391
DOI: 10.1021/acsnano.0c04174

Abstract

The formation of wurtzite (WZ) phase in III-V nanowires (NWs) such as GaAs and InP is a complication hindering the growth of pure-phase NWs, but it can also be exploited to form NW homostructures consisting of alternate zincblende (ZB) and WZ segments. This leads to different forms of nanostructures, such as crystal-phase superlattices and quantum dots. Here, we investigate the electronic properties of the simplest, yet challenging, of such homostructures: InP NWs with a single homojunction between pure ZB and WZ segments. Polarization-resolved microphotoluminescence (μ-PL) measurements on single NWs provide a tool to gain insights into the interplay between NW geometry and crystal phase. We also exploit this homostructure to simultaneously measure effective masses of charge carriers and excitons in ZB and WZ InP NWs, reliably. Magneto-μ-PL measurements carried out on individual NWs up to 29 T at 77 K allow us to determine the free exciton reduced masses of the ZB and WZ crystal phases, showing the heavier character of the WZ phase, and to deduce the effective mass of electrons in ZB InP NWs (m_e= 0.080 m₀). Finally, we obtain the reduced mass of light-hole excitons in WZ InP by probing the second optically permitted transition Γ₇^C ↔ Γ_7u^V with magneto-μ-PL measurements carried out at room temperature. This information is used to extract the experimental light-hole effective mass in WZ InP, which is found to be m_lh = 0.26 m₀, a value much smaller than the one of the heavy hole mass. Besides being a valuable test for band structure calculations, the knowledge of carrier masses in WZ and ZB InP is important in view of the optimization of the efficiency of solar cells, which is one of the main applications of InP NWs.

Keywords: InP nanowires; carrier effective mass; crystal-phase homostructures; excitons; light hole; magneto-photoluminescence; wurtzite and zincblende.