Verification of an Compact Model for Organic Thin-Film-Transistors by Using MixedMode Creating an CMOS Inverter Circuit with TCAD Transistor Devices
Jakob Pruefer (1,2), Alexander Kloes (1), Ahmed Nejim (3)
(1) NanoP, TH Mittelhessen University of Applied Sciences, Giessen, Germany
(2) DEEEA, Universitat Rovira i Virgili, Tarragona, Spain (3) Silvaco Inc., St. Ives, United Kingdom
Organic thin-film transistors (OTFTs) are promising devices for future low-cost electronics[1][2]. However, to enable the development of this technology, circuit design simulation is needed. TCAD with MixedMode approach provides a suitable route for the physics based simulation of these transistors within simple circuits. As circuits become more complicated, more devices are needed and the computing time increases significantly. Compact models describe the behavior of the device with only a few equations and thus the computing time is reduced to a viable magnitude. Such equations are written down in a Verilog-A format which can be used by most SPICE simulators.
These compact models have to be verified through comparison with measurements and/or TCAD simulation data. A MixedMode simulation provides a small SPICE-like circuit with TCAD devices.
In this article MixedMode is used to simulate a CMOS inverter circuit as in Figure 1 with two OTFTs, both of which are expressed as TCAD models using the Atlas simulator. Ultimately, four CMOS inverters are simulated with the following channel lengths of 0.3, 1, 2 and 10 microns. Subsequently the compact model is fitted to the MixedMode simulation data of the CMOS inverter with a channel length of 2 microns. The further scaling from 10 microns down to 0.3 microns simulations were done using the same fitting parameters in order to test the scalability of the proposed compact model.
