TFT Structure with Electronically Adjustable Threshold
Original Publication Date: 1978-May-01
Included in the Prior Art Database: 2005-Feb-21
The gate threshold voltage is one of the most important device parameters of a thin-film transistor (TFT), but requires highly reproducible manufacturing processes to achieve a prescribed value over a batch of devices. To overcome this problem a thin-film transistor having the usual gate electrode 1, semiconductor channel 2, and source and drain electrodes 3 and 4, respectively, is also provided with an additional electrode 5, called a field plate, which can be used, as shown in Fig. 2, to modify the Gsd/Vg characteristics by varying the field plate potential Vfp. The field plates can be made common to all devices on a substrate so that all can simultaneously be biased. The field gate also acts as a shield, and can be used as an additional logic input to the transistor.