Superb Low Threshold Surface-Plasmon Polariton ZnO Nanolasers on an Aluminum Film with Tailored MoO₃ and Ta₂O₅ Dielectric Interlayers of Varied Thickness

Abstract

Effects of high-k dielectric MoO 3 and Ta 2 O 5 interlayers on the lasing thresholds of ZnO/high-k material/Al nanolasers have been investigated. The results demonstrated the highdielectric-constant materials as the interlayers over the epitaxially grown aluminum (Al) film consisting of high-quality ZnO nanowires constructing superb low threshold surface-plasmon polariton lasers. High-quality ZnO nanowires grown via the chemical vapor deposition process were used as the gain media placed over a single-crystalline Al film deposited via molecular beam epitaxy. For high metallic losses in the Al film, high k-dielectric material films (MoO 3 and Ta 2 O 5 ), deposited using the electron beam technique, are inserted in the midst of the Al film and ZnO nanowires to reduce the material losses and enhance the optical confinement. It has been found that the lasing threshold varies with the increasing thickness and reduces while increasing the dielectric constant. The performances are compared with those of similarly fabricated nanolasers with Al 2 O 3 and WO 3 dielectric interlayers. The critical roles of dielectric constants of the dielectric interlayers in influencing the thresholds of lasing are elucidated. Highly suppressed losses in lasing can be attributed to the dielectric layer that manifests the strong energy confinement in the sub regime. It also shows that the correlation of the lasing threshold with the dielectric constant value applies mainly to the same laser system. For different systems, other factors such as the crystallinity and defects present should be taken into consideration.