Voltage-controlled device thin-film transistor

For high information-content displays, active-matrix (AM) pixel addressing provides improved display performance and reduced power consumption. In active matrix addressing each individual pixel is controlled by one or more thin-film transistors (TFTs). To date, most AM OLED displays have used polysilicon TFTs as the active elements, because they can provide sufficient current at low voltages and acceptable device dimensions, and they are capable of integrated drive electronics... 

The typical a-Si H thin film transistor (TFT) is a field-effect device, shown schematically in Figure 8.13. The electrodes are patterned on a glass substrate and the gate is covered by a dielectric, usually Si3N4. The active a-Si H layer is added on top of the dielectric and the device is finished with source and drain electrodes. Application of a bias voltage to the gate controls channel conductivity as usual in field-effect transistors. These switch power onto and off of electrodes in displays quickly and efficiently. 

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