Study On The Properties And Growth Mechanism Of Ultrathin Ag/V Transparent Films Grown By Unbalanced Magnetron Sputtering

Indium tin oxide(ITO)film is the most widely used transparent conductive film in the market.However,it suffers from poor flexibility,high production cost,and usually requires high-temperature annealing,which limit its application in flexible optoelectronic devices such as bendable and wearable devices.Ultra-thin Ag film is expected to be a substitute for ITO film.It has good flexibility,electrical conductivity and light transmittance,which can be used in large-scale manufacturing and has great application potential in the field of flexible optoelectronic devices.However,the three-dimensional island growth pattern of Ag thin films on the substrate results in rough surface and poor continuity,which limits its application in various photoelectric devices.In this paper,the effects of deposition parameters on the surface morphology,deposition rate and crystallinity of V and Ag thin films were studied by non-equilibrium magnetron sputtering.Finally,a continuous ultra-thin Ag film with a thickness of only 6 nm was obtained by pre-deposition of a metal V-seed layer with high surface energy.The effects of V-seed layer on the microstructure,substrate wettability,optical and electrical properties of the ultrathin Ag film were studied.The results show that:(1)When the sputtering power is 15 W,the surface of the V film is smooth and dense,and the surface roughness and deposition rate of the film are 1.6 nm and 4.4nm/min.With the increase of sputtering power,the surface roughness,deposition rate and crystallization of the film all grow.The V films deposited under the sputtering power of 15-45 W are all grown in the <110> preferred orientation.(2)As the sputtering power increased from 15 w to 45 w,the deposition rate of the Ag film increased from 21.3 nm/min to 54.3 nm/min,and the average surface particle size increases from about 50 nm to about 100 nm,while the change trend of surface roughness is to increase first,then decrease and then increase.The deposition rate of the Ag film under 0.3 Pa is 20.4 nm/min.When the working pressure is 1.5 Pa,the surface roughness and average particle size of the film are the smallest,which are1.9 nm and 46.7 nm,respectively.The Ag films deposited at the sputtering power of15-45 W and the working pressure of 0.3-1.5 Pa are all preferentially grown in the<111> direction.(3)The V seed layer with high surface energy,can act as heterogeneous nucleation site of Ag atoms,thus inhibiting the surface migration Ag atoms and reducing the surface energy mismatch between Ag and glass substrates,thereby promoting the transformation of Ag atoms from island growth mode to two-dimensional layered growth mode.Finally,the threshold thickness of the ultrathin Ag film is reduced from 6 nm without the seed layer to 4 nm.At the same time,the surface roughness of the 6 nm-thick ultra-thin Ag film is only 0.6 nm,the sheet resistance is 15.3 Ω/sq,and the average light transmittance is up to 81.8% in the wavelength range of 300-800 nm.