A system and method of managing content distribution is disclosed. The system includes a constant power source and a plurality of motors having electrical circuits with switches to connect with the constant power source. High tensile stress may also be achieved by exposing a surface to a silicon-containing precursor gas in a first nitrogen-containing plasma, treating the material with a second nitrogen-containing plasma, and then repeating these steps to increase a thickness of the silicon nitride formed thereby. Then a current value IDS of the TFT is hardly changed by VDS but is determined solely by VGS.