Claire Blaga1,Michele Zendrini1,Osman Balci2,Sachin Shinde2,Soham Joshi1,Victor Bugnion1,Andrea Ferrari2,Anna Fontcuberta i Morral1,3,Valerio Piazza1
Ecole Polytechnique Federale de Lausanne1,University of Cambridge2,École Polytechnique Fédérale de Lausanne3
Claire Blaga1,Michele Zendrini1,Osman Balci2,Sachin Shinde2,Soham Joshi1,Victor Bugnion1,Andrea Ferrari2,Anna Fontcuberta i Morral1,3,Valerio Piazza1
Ecole Polytechnique Federale de Lausanne1,University of Cambridge2,École Polytechnique Fédérale de Lausanne3
Transition metal dichalcogenides (TMDs) have high spin-orbit coupling (spin splitting energies between 0.1 and 0.5 eV [1]), exciton funneling [2] and strain modulation [3] which may allow them to be core semiconductors in a wide variety of devices. The ability to tune their properties by applying localized strain is appealing in fields ranging from electronics [4] to photonics [5], from spintronics [6] to optoelectronics [7]. The combination with 1D nanostructures could be used to control the strain distribution in monolayers (1Ls) as the morphological reshaping of the TMDs on nanowires (NWs) results in a localized strain [5,6]. III-V NWs can enable control over charge and exciton injection into 1L-TMDs. Heterostructures made of 1L-TMDs on horizontal III-V NWs exhibit interesting optical properties in view the design of quantum emitter arrays [8]. However, the impact of material stacking, geometry and NW size on the strain distribution and the consequent effect on the optical properties must be clarified.<br/>Here, we report on hybrid heterostructures made of 1L-WSe<sub>2</sub> on horizontal GaAs NWs. The 1L-WSe<sub>2</sub> is grown on sapphire by water-assisted chemical vapor deposition (CVD) using WSe<sub>2</sub> bulk as the presursor. Selective area epitaxy molecular beam epitaxy (SAE-MBE) is used to grow ordered arrays of faceted III-V NWs, differing by width and height and NW-to-NW distance. After GaAs surface passivation with ammonium sulphide, 1L-WSe<sub>2</sub> is placed on the horizontal NWs via wet transfer using polymethyl methacrylate as the support layer. Micro-photoluminescence and Raman mapping are performed at room and low temperature to outline the variation of optical features with the NW array parameters. Numerical simulations support the strain distribution description, consistently with the experimental optical maps.<br/><br/><br/><br/><b>References</b><br/>[1] Bangar et al., ACS Appl. Mater. Interfaces 14, (2022)<br/>[2] Moon et al., Nano Lett. 20, (2020)<br/>[3] Manzeli et al., Nat.Rev.Mater. 2, (2017)<br/>[4] Datye et al., Nano Lett. 22, (2022)<br/>[5] Palacios-Berraquero, Nat. Commun. 8, (2017)<br/>[6] Mukherjee et al., Nat. Commun. 11, (2020)<br/>[7] Lopez-Sanchez et al., ACS Nano 8(3), (2014)<br/>[8] Jasinski et al., 2D Mat. 9, (2022)