High-Performance Thin-Film Transistors in Disordered and Poor-Quality Semiconductors

Abstract

Abstract-In general, the range of applications for large-area electronics or macroelectronics is limited by the quality of the semiconductor used to make the electronic devices and circuits. Here, we address the question of how to make high-performance transistors using semiconductors that are defective, have low carrier mobilities, and are unstable. It is proposed that we need to engineer and operate a transistor that minimizes the excess carrier concentration throughout the device combined with high internal fields over small dimensions. Compared with the fieldeffect transistor, a source-gated transistor more nearly meets these requirements. Using the unstable and defective semiconductor, hydrogenated amorphous silicon, it is shown that high-performance thin-film transistors can indeed be made using the source-gated concept.

Effects of process variations on the current in Schottky Barrier Source-Gated Transistors

“…Keeping d under 1μm also has some other advantages such as the possibility of operating at lower gate bias for high current output and high switching speed. In organic materials in which the effective carrier mobility is drain field dependent, a short source-drain gap leads to increased electrical field and faster device operation [6], [7].…”

Source-gated thin-film transistors

“…[10]) we showed how transistor characteristics of the SGT are superior to those of a FET with d = L = 250 nm. In Fig.…”

“…Furthermore if we want to reduce carrier transit times to obtain high speeds then we must increase the internal electric field throughout the TFT and reduce device dimensions. The SGT is able to provide all of these requirements for stable high speed performance [10].…”

High Performance Transistors in Low Mobility Organic Semiconductors for Analog and High-Frequency Applications

“…Drive current and frequency response As discussed in [14], the way to obtain high drive current and a good frequency response for a given geometry transistor despite having a low carrier mobility is to operate with high internal fields over short distances to reduce carrier transit times combined with low carrier concentrations for low capacitance. The simulations show that the electric field along the interface for the SGT at the edge of the source, where most of the current flows [8], is as much as six times greater than in the corresponding FET [14]. Because both the carrier velocity and charge mobility are field-dependent in the organic material, much higher internal electric field in OSGT brings higher drive current than that in the OFET when the low field mobility is small, as shown in Fig.…”