Anti-reflection behavior of a surface Ga-doped ZnO nanoneedle structure and the controlling factors
Journal
Optical Materials Express
Journal Volume
7
Journal Issue
11
Date Issued
2017
Author(s)
Yao, Y.-F.
Yang, S.
Lin, H.-H.
Chou, K.-P.
Weng, C.
Liao, J.-Y.
Lin, C.-H.
Chen, H.-T.
Su, C.-Y.
Tu, C.-G.
Abstract
The anti-reflection functions of a surface nanostructure-including transparent conductive Ga-doped ZnO (GaZnO) nanoneedles (NNs), a GaZnO thin film, and buried Ag nanoparticles (NPs), on GaN and Si templates through the combination of the effects of gradient effective refractive index, index matching, and the surface plasmon (SP) resonances in the visible and infrared range-are studied by measuring its reflection, transmission, and scattering behaviors. The NNs are grown under different molecular beam epitaxy conditions with the low-temperature vapor-liquid-solid mode by using Ag NPs as growth catalyst. Based on the crystal structure study, it is found that the c-axis of a GaZnO NN is controlled by the local Ag (111) orientation of the un-melted portion of an Ag NP, which is influenced by the crystal structure of the growth template. On c-plane GaN, by using small and separate Ag NPs as catalysts, the alignment of GaN (002), Ag (111), and ZnO (002) leads to the growth of mostly vertical NNs for producing a strong anti-reflection effect. On Si (100), no crystal matching condition can be used such that the grown NNs are randomly oriented, leading to a relatively weaker anti-reflection effect. The GaZnO thin film and buried Ag NPs also make contributions to the anti-reflection function through the effects of index matching and SP resonance.
SDGs
Type
journal article