Explanation

Thin films with conductive functions. The charged carriers of conductive films are scattered by the surface and interface during transportation. When the thickness of the film can be compared to the free path of electrons, the influence on the surface and interface becomes significant, which is called the size effect of the film. It is equivalent to the reduction of the free path of the carrier, so the electric conductivity of the film is smaller than that of the block of the same materials. Due to incomplete preparation techniques, the defect concentration in the thin film is usually relatively high. The main defects are impurities, vacancy, interstitial atoms, dislocation, grain boundary, and adsorption and segregation on the surface and interface. These defects scatter or capture the carrier, thus reducing the free path and lifetime of the carrier, which also causes the reduction of the electric conductivity of the film. The formation process of thin films is divided into four stages: nucleation, growth, connection into maze, and continuous film formation. If it stops at any stage, it becomes a different structural film, such as the film before the particle connection, becoming a particle film. The conductivity of particle films involves the transfer of electrons between separated particles. The conduction mechanism is complex. There are two main theories: firstly, tunneling conduction, where the barrier between particles is narrow, and electrons pass through the barrier through the tunneling effect? Transfer between particles: the second is thermal electron emission conduction, which transfers electrons between particles by thermal emission mechanism and plays a major role at higher temperatures. Some thin films indirectly complete the conductive process of the particle film through charge transfer between the particles and the substrate.

Classification