Extremely high-gain source-gated transistors

Abstract

Despite being a fundamental electronic component for over 70 years, it is still possible to develop different transistor designs, including the addition of a diode-like Schottky source electrode to thin-film transistors. The discovery of a dependence of the source barrier height on the semiconductor thickness and derivation of an analytical theory allow us to propose a design rule to achieve extremely high voltage gain, one of the most important figures of merit for a transistor. Using an oxide semiconductor, an intrinsic gain of 29,000 was obtained, which is orders of magnitude higher than a conventional Si transistor. These same devices demonstrate almost total immunity to negative bias illumination temperature stress, the foremost bottleneck to using oxide semiconductors in major applications, such as display drivers. Furthermore, devices fabricated with channel lengths down to 360 nm display no obvious short-channel effects, another critical factor for high-density integrated circuits and display applications. Finally, although the channel material of conventional transistors must be a semiconductor, by demonstrating a high-performance transistor with a semimetal-like indium tin oxide channel, the range and versatility of materials have been significantly broadened.

Compact Source-Gated Transistor Analog Circuits for Ubiquitous Sensors

“…The source-gated transistor (SGT) is a TFT structure with operating mechanisms considerably different from conventional FETs [22]. The SGT has shown remarkable benefits: lower saturation voltages, high gain, low power consumption and, notably, superior uniformity and electrical robustness [23]- [26]. There are, however, drawbacks arising from the reduced current density (due to charge injection over an energy barrier purposely introduced at the source) and increased capacitance (as a result of the staggered source and gate electrodes): relatively low transconductance gm and operating frequency fT [27], [28], respectively.…”

“…1a and 1b show cross-sections of two SGTs with sourcegate overlap S and source-drain separation, d. (SGTs ordinarily do not use the more general notation L for sourcedrain gap, as their effective channel length varies with applied bias in a manner additional to channel length shortening in FETs, hence the distinct terminology). SGTs have been explored in a variety of materials including amorphous [29] and polysilicon [23], [25], [28], [30], ZnO [31], InGaZnO (IGZO) [26], [32], organics [33], MoS2 [34] and semimetals [26], with several means of engineering an energy barrier at the source, including Schottky contacts ( Fig. 1a), bulk unipolar contacts [35], [36], or incorporating a tunnel barrier [32] (Fig.…”

8.4: Invited Paper: Oxide devices for displays and low power electronics

“…In order to realize further advancement, it is necessary to design new transistors with improved performance. Here we present a novel transistor, called the source-gated transistor, by combining the Schottky source with the TFT [15] . The cross-sectional schematics and the output curves of the conventional TFT and the SGT are shown in Figures 5(a) to 5(d).…”

“…Here, we review our recent work on a) high-performance oxidebased Schottky diodes with an ideality factor of 1.09, ultra-low noise, and operating speed >20 GHz on glass [2] and 2.45 GHz on flexible substrate [3] ; b) IGZO TFTs capable of reaching a benchmark speed of 1 GHz [4] , which are, to the best of our knowledge, the fastest oxide-based diodes and transistors to date; c) a few different methods to achieve IGZO TFTs capable of onevolt operations [5][6][7][8][9] ; d) CMOS-like oxide logic gates and functional circuits including inverters with a gain up to 150 [10,11] , NAND gate [12] , D-latch [13] , 51 stage ring oscillator [13] , complementary static random access memories [14] , and a one-bit full adder [13] , etc, by integrating SnO-based p-type TFTs with IGZO-based n-type TFTs; and finally e) novel oxide TFTs with a Schottky source contact that show no short channel effect, almost total immunity to negative bias illumination stress, and have a gain over two orders of magnitude higher than that of a typical silicon transistor [15] .…”

Fundamentals of Organic Anti‐Ambipolar Ternary Inverters

“…A key merit of simulation is to precisely solve position‐dependent physical quantities inside a semiconductor, which are often difficult to probe experimentally 24–28. By navigating the internal flows of our inverter, we discovered that the charge‐carrier behaviors and associated conduction properties differ drastically at each of the three regimes.…”