Influence of Space Charge Carriers and Active Plasma Components of DC Townsend Discharge on the Surface Transformation of Nano-Sized Bi Films

Under the conditions of low-temperature plasma, this work proposes a new controllable express method for transformation of nano-sized Bi films into semiconducting Bi2O3 films in a modified plasma microreactor with GaAs photosensitive plate. The transformation mechanism of Bi films depends on the current density, charge transferred, and exposure time. From the mechanism of formation of Bi2O3 semiconductor film, we have established: 1) that this is a surface process that moves deeper into the Bi film when the operation parameters change; 2) the band gap value of the Bi2O3 semiconductor film obtained from Tauc’s plot is Eg ≈ 3 eV; 3) that this process is provided by the combined kinetic energy of electrons and oxygen ions.