Photonic and Electronic Interaction of TMD-Hybridized ZnO Nanowire Lasers

Abstract

Semiconductor nanowire lasers are promising on-chip coherent light sources for photonic integrated circuits, but integration inevitably places them in contact with other materials, thereby changing their properties upon hybridization. In this study, we examine the photonic and electronic coupling between single ZnO nanowire lasers and TMDs. Using deterministic nanomanipulation, we first hybridized the same nanowire first with a WS$_2$ monolayer and then with a MoS$_2$ monolayer. The respective lasing threshold rises, the emission is strongly quenched at high pump power densities, and the mode envelope blueshifts. Upon hybridization with bilayer, trilayer, and bulk MoS$_2$, lasing is fully suppressed. Finite-Difference Eigenmode simulations show that the TMD absorbs part of the evanescent field. Because this absorption is wavelength dependent, it also removes modes from the low-energy flank of the envelope, which accounts for small difference between the two monolayers, while the blueshift itself follows the increase of the carrier density at threshold. Density functional theory calculations that include the interface dipole predict a type-I alignment at the ideal ZnO(10$\bar{1}$0)/TMD interface, which turns into type~II for a moderately reduced dipole, as expected for hydroxylated facets in air. In both cases, holes are transferred from the nanowire into the TMD and removed from the gain medium. Evanescent absorption and hole transfer thus jointly suppress lasing, and both must be accounted for when integrating nanowire lasers with 2D materials.