Dependence of the piezoactivity of zinc oxide films on the conditions of synthesis in critical regimes of glow discharge

The influence of the gas pressure in a magnetron sputtering system on the efficiency of volume hypersound generation in the synthesized ZnO films has been experimentally studied at pressures close to the transition from glow discharge to Townsend regime, whereby the ion and electron mean free path length increases and a drift component appears in the flux of deposited particles. It is established that the efficiency of hypersound generation (at a frequency above 1 GHz) in ZnO films deposited under these conditions increases. Based on a comparison to the properties of films deposited in a classical diffuse glow discharge, this result is explained by a lower nucleation texture and higher density of the films grown in a critical regime.