NMOS silicon gate transistors in large-area laser-crystallised silicon layers

The properties of NMOS polycrystalline silicon gate transistors, fabricated in large-area laser-crystallised silicon layers on an insulating substrate, are described. The transistor characteristics reveal the influence of parasitic side transistors. The influence of the side-channel transistors becomes more pronounced with decreasing channel width, and has to be considered in the mobility calculations. The electron mobility is channel-length dependent, and varies from 780 sq cm/V per sec at L = 5 microns to 200 sq cm/V per sec at L = 100 microns. Leakage currents at 4.9 V are typically 15 pA/micron; although 20 percent of transistors with channel length less than 10 microns show leakage currents in excess of 1 milliampere. The threshold voltage depends on the drain voltage, as is typical for silicon-on-insulator structures.