Ultrasmooth and Thermally Stable Silver-Based Thin Films with Subnanometer Roughness by Aluminum Doping

Abstract

Rough surface and poor stability of ultrathin Ag films limit their applications in nanophotonic and optoelectronic devices. Here, we report an approach for fabricating ultrasmooth and thermally stable Ag-based thin films on SiO2/Si substrates by Al-doping. The effect of Al-doping on the surface morphology and stability of ultrathin Ag films at room temperature and elevated temperature was investigated. The 15 nm Al-doped Ag films with an Al atomic concentration of 4% have a root-mean-square roughness as low as 0.4 nm. The smooth surface morphology is maintained even after 300 °C annealing in N2. Al-doping enhances the nuclei density of films. Moreover, a capping layer spontaneously formed over the Al-doped Ag films restrains the surface diffusion and mass transportation of Ag atoms. Therefore, Al-doping induces ultrathin Ag films with highly stable and ultrasmooth surface morphology.

Transparent electrode of nanoscale metal film for optoelectronic devices

“…Several approaches to use an ultrathin (<10 nm) Ag electrode have been reported. [38][39][40][41][42][43][44][45][46][47][48][49] As the OT of the electrode increases, its emission spectrum broadens, in agreement with theoretical expectations for a weak microcavity. 56 Using a weak microcavity also increases the angular color stability and the device efficiency.…”

“…76 This dewetting tendency of pure Ag becomes more obvious at elevated temperatures. 57,77 Zhang et al 48 and Gu et al 49 used Al doping to fabricating ultrathin (3 nm) Ag-based thin films with high thermal stability on SiO 2 ∕Si (100) substrates. Al doping yielded smaller and denser nuclei [ Fig.…”

“…Ultrathin Ag electrodes are promising for this function because the OT and R s of these electrodes are comparable to or better than those of ITO electrodes. [38][39][40][41][42][43][44][45][46][47][48][49] In addition, their mechanical properties are appropriate for use in flexible devices. 40 This review highlights recent progress in the fabrication of nanoscale thin Ag electrodes.…”

Flexible and Semitransparent Organic Solar Cells

“…However, ultrathin metal films (UTMF) deposited by physical vapor deposition techniques tend to grow with island-like mode (VolmerWeber growth mode), consequently exhibit a rough surface morphology with large grain size and high electrical resistivity, which severely affect the performance of the devices. [99,100] Thus, achieving thin and smooth Ag films under low evaporation temperature is crucial for their application in flexible transparent electrode. Transparent metal oxide is commonly used as seed layer to achieve high quality UTMF through optimized wettability and chemical interactions between Ag and metal oxide.…”

Circularly Polarized Light Detection with Hot Electrons in Chiral Plasmonic Metamaterials

“…The plasmonic metamaterial was fabricated by first depositing a 1-nm-thick titanium layer (forming the Schottky barrier) followed by a 45-nm-thick aluminum-doped silver film 39 . Aluminum-doped silver was used due to the fact that it helps to reduce the silver film roughness and grain size while also facilitating the formation of an Al 2 O 3 passivation layer that protects the silver from corrosion 39 . The experimentally measured optical absorption spectrum of both the LH and RH metamaterial reveals the same absorption bands demonstrated in the simulations.…”