Characteristics of double-gate polycrystalline silicon thin-film transistors for AMOLED pixel design

The performance of n-channel symmetrical double-gate (DG) polycrystalline silicon thin-film transistors (polysilicon TFTs) has been investigated with 2-D device simulations. The simulations were conducted based on device characteristic properties, extracted from fabricated single-gate (SG) polysilicon TFTs. Through fitting of the test SG devices, a unique set of density of states was identified, that characterizes the particular technology used. The obtained results reveal that DG TFTs, due to their enhanced gate controllability, exhibit steeper subthreshold slope, lower threshold voltage, higher driving current and better device uniformity compared to their SG counterparts. Implementation of DG TFTs in 2T1C active matrix circuit show that the response time of the circuit can be improved by eight times compared with the conventional SG TFTs and exhibit more stable driving capability due to the improved device uniformity.