M.S. Shur, X. Liu, T. Ytterdal
Rensselaer Polytechnic Institute,
Keywords: thin film transistor, printed electronics
Summary:Recent breakthroughs in Thin Film Transistor (TFT) materials technology1 with field effect mobilities reaching or even exceeding those for silicon CMOS (see Fig. 1) have been truly transformational.Coupled with the minimum feature sizes down to and below 50 nm 2 over areas as large as 2x2 m2 makes the TFT technology superior even to Si CMOS for many applications. The advanced TFT technology is now have a potential of detecting and processing higher frequency radiation reaching all the way into 240-320 GHz range3, which is a transmission window for sub-THz propagation in Earth atmosphere. 4 Hence, there is potential for the 6G applications of advanced ultra-short channel TFTs, including WI-FI 6G. 5 Other key applications of the high field effect mobility TFTs is the 3D integration of the advanced ultra-short channel TFTs with Si CMOS and 3D TFT structures, such as the “folded gate” inverters6 (see Fig. 2). The predictions and investigations of these transformational applications require accurate and validated compact models suitable for device characterization, parameter extraction, yield and reliability predictions, and circuit design. In this paper, we describe a new generation of the RPI TFT model 7 (see Fig. 3) that uses the channel segmentation that is important at higher frequencies. The new model first computes the field distribution in the channel and predicts the frequency dependent number of the channel segments required to reproduce the channel dispersion with the sufficient accuracy. Then the calculated field profile is used to evaluate the segment parameters that include the segment impedance, kinetic (Drude) inductance, and gate to segment capacitances. This approach gracefully degrades to the conventional RPI TFT model at low frequencies that is used for fitting the TFT DC characteristics. Future plans include high frequency circuit designs, such as described in 8. 9 for different TFT materials system and feature sizes.