Deposition of ultrasmooth silver nanolayers at pressures and temperatures above the sublimation point of water ice

Abstract

A new method of deposition of ultrasmooth silver nanolayers at pressures and temperatures above the sublimation point of water ice in electron-beam evaporator is proposed and discussed. We balance contradictory influences of several phenomena involved in physical vapour deposition process. Deposition of metal-dielectric multilayers on cooled substrates creates a problem with dimensional stability against temperature changes. Mismatch of thermal expansion coefficients of layers gives rise to intrinsic stress what results in metal film cracking. Too strong cooling of substrates leads to water ice crystals formation on substrates at temperatures smaller than sublimation phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram. Surface roughness of 30 nm thick Ag layer deposited on 1 nm Ge wetting film on sapphire substrate described in terms of root mean square (RMS) error reaches 0.5 nm. This research is motivated by the need to suppress plasmon losses due to scattering on surface roughness.