Field Effect Transistors
The field-effect transistor (FET) is a transistor that relies on an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are sometimes called unipolar transistors to contrast their single-carrier-type operation with the dual-carrier-type operation of bipolar (junction) transistors (BJT). The concept of the FET predates the BJT, though it was not physically implemented until after BJTs due to the limitations of semiconductor materials and the relative ease of manufacturing BJTs compared to FETs at the time. (Wikipedia, Field Effect Transistors, 12/7/2011)
Recent Journal Articles
Molecular Weight-Induced Structural Transition of Liquid-Crystalline Polymer Semiconductor for High-Stability Organic Transistor
( 4442–4447)Advanced Functional Materials 21 #23 (2011)
Kim et al, South Korea and California, fabricated polymer field-effect transistors (PFETs) with high electrical stability under bias-stress, by minimizing the density of charge trapping sites caused by the disordered regions. Here we report PFETs with excellent electrical stability comparable to that of single-crystalline organic semiconductors by specifically controlling the molecular weight (MW) of the donor-acceptor type copolymer semiconductors, poly (didodecylquaterthiophene-alt-didodecylbithiazole). We found that MW-induced thermally structural transition from liquid-crystalline to semi-crystalline phases strongly affects the device performance (charge-carrier mobility and electrical bias-stability) as well as the nanostructures such as the molecular ordering and the morphological feature. This enhancement of the electrical bias-stability can be attributed to highly ordered liquid-crystalline nanostructure of copolymer semiconductors on dielectric surface via the optimization of molecular weights. (RDC 12/6/2011)