Thin Film Transistors

Components Of A TFT

Individual pixel on a notebook LCD screen has a transistor called a thin-film transistor. The transistor on each pixel allows the current that helps pixel illumination can be smaller, allowing it to be switched on and off quickly. The TFT helps improve image quality and reduces crosstalk between the pixels.

The TFT is made up of three different components: the gate, source and drain source. The gate is separated from the semiconductor by a gate insulator layer. The source and drain source are in contact with the semiconductor.

To turn the TFT on, a positive charge is applied to the gate. Within the semiconductor channel, a negative charge is created and opens a conductive channel allowing electrons to flow from the source to the drain. However, if a negative charge is applied to the gate, electrons are lost and negligible current begins (the TFT is turned off).

While the TFT is on, the drain that holds the liquid crystal load will meet the voltage as the source and the data signal from the data line to the pixel is sent.

Some other types of TFTs have the source and the drain overlapping with the gate. This causes a parasitic capacitance that may alter the display. A parasitic capacitance is capacitance that is not wanted when attempting ideal circuit elements.