Study on Ultrathin Silver Film Transparent Electrodes Based on Aluminum Seed Layers with Different Structures

Abstract

Ag has the lowest electrical resistivity among all metals, and at the same time, the best optical properties in the visible and near-IR spectral range; it is therefore the most widely employed material for thin-metal-film-based transparent conductors. In this work, an ultra-thin transparent silver film electrode with aluminum as seed layer was prepared by a resistive thermal evaporation technique. Using a range of electrical, optical and surface morphology techniques, it can be noted that the presence of the thin layer of aluminum changes the growth kinetics (nucleation and evolution) of the thermal evaporation of Ag, leading to silver films with smooth surface morphology and high electrical conductivity, and the threshold thickness of the silver film is reduced. It is inferred that the aluminum layer showed a good infiltration effect on the ultra-thin silver film, by analyzing the transmittance spectrum, sheet resistance and surface morphology. Moreover, the average transmittance of silver film with 10 nm is 40% in the 400–2500 nm band, whereas the sheet resistance is 13 Ωsq −1. A series of experiments show that the introduction of Al seed layer has certain effect on improving the properties of transparent conductive silver films. Then, a new method for deposition of 1 nm Al seed layer was proposed; that is, the 1 nm aluminum infiltrated layer is divided into two or more layers, and the average transmittance of silver film with 5 nm is 60% in the 400–2500 nm band, whereas the sheet resistance does not exceed 100 Ω sq−1.

Overcoming Challenges in OLED Technology for Lighting Solutions

“…A critical aspect to overcome to make it a suitable option for a transparent metal electrode is achieving perfect surface coverage at low thicknesses, i.e., a 2D continuous silver film capable of ensuring good conductivity and promoting charge injection. The silver layer normally follows the 3D island formation method known as Volmer-Weber growth [155], in which Ag agglomeration occurs due to the stronger cohesive forces among Ag clusters compared to the adhesion forces at the metal and substrate interface. This prevents the precise deposition of a single ultrathin Ag film with low resistivity and good uniformity.…”

Ultra-thin silver films grown by sputtering with a soft ion beam-treated intermediate layer

“…Various methods have been studied to enhance the wettability of silver to substrates and grow ultra-thin continuous and dense silver films. A primary method is to grow a wetting layer such as Ge [8][9][10], Cu [11,12], Ni [13], Al [14], oxygen-incorporated silver films (Ag (O) ) [15][16][17][18], and aluminum doped zinc oxide (AZO) [19]. Other methods such as using silver alloys were also reported [1,5].…”

Insight into the High Mobility and Stability of In2O3:H Film

“…Transparent conductors, which usually require high optical transparency and high electrical conductivity, are necessary for photovoltaics, photodetectors, light-emitting diodes, and other optoelectronic devices. The ultra-thin metals, [1,2] conducting polymers, [3][4][5] carbon nanotubes, [6][7][8] and especially graphene [9][10][11][12][13] have been extensively considered in recent years, while they have not yet been able to replace the mainstream DOI: 10.1002/smll.202304721 transparent conductor oxides (TCO) since it is a challenge for them to combine the high light transmittance and the high electrical conductivity. Besides, TCOs such as ZnO:Al (AZO), [14][15][16][17][18] SnO 2 :F (FTO) , [19][20][21][22][23] and In 2 O 3 :Sn (ITO) [24][25][26][27] have excellent chemical and environmental stability and nontoxicity, and their conductivity can be flexibly tuned by changing the doping density in a wide range from 10 15 to 10 22 cm −3 .…”