Significance Source-gated transistors (SGTs) exhibit high intrinsic gain, immunity to bias instability, low-power consumption, and tolerance to short-channel effects, and thus are attractive candidates for wearable devices. However, few studies have addressed the potential of metal oxide semiconductor (MO)-based SGTs. Here we demonstrate solution-processed MO SGTs based on a semiconductor homojunction, comprised of solution-processed In2O3 and In2O3:PEI polymer blend layers of controlled doping, exhibiting low saturation voltage, low-power consumption, and high intrinsic gain. Furthermore, electrooculographic signal monitoring is demonstrated using an SGT inverter, which provides a voltage gain of over 300 and is readily suitable for applications in wearable medical sensing.

High-performance and low-power source-gated transistors enabled by a solution-processed metal oxide homojunction

Power consumption makes next-generation large-scale photodetection challenging. In this work, the source-gated transistor (SGT) is adopted first as a photodetector, demonstrating the expected low power consumption and high photodetection performance. The SGT is constructed by the functional sulfur-rich shelled GeS nanowire (NW) and low-function metal, displaying a low saturated voltage of 0.61 V ± 0.29 V and an extremely low power consumption of 7.06 pW. When the as-constructed NW SGT is used as a photodetector, the maximum value of the power consumption is as low as 11.96 nW, which is far below that of the reported phototransistors working in the saturated region. Furthermore, benefiting from the adopted SGT device, the photodetector shows a high photovoltage of 6.6 × 10-1 V, a responsivity of 7.86 × 1012 V W-1, and a detectivity of 5.87 × 1013 Jones. Obviously, the low power consumption and excellent responsivity and detectivity enabled by NW SGT promise a new approach to next-generation, high-performance photodetection technology.

New Approach to Low-Power-Consumption, High-Performance Photodetectors Enabled by Nanowire Source-Gated Transistors.

The first flexible source-gated transistors (SGTs) in microcrystalline silicon have been fabricated and characterized under bending stress. As SGTs are contact controlled devices, the channel does not modulate drain current, however its geometry has implications for operation. We show how reduced channel length in SGTs helps promote negligible threshold voltage shifts when strain is introduced with a radius of r = 2.5 mm.

Flexible Microcrystalline Silicon Source-Gated Transistors with Negliglible DC Performace Degradation at 2.5 mm Bending Radius

As amorphous oxide semiconductors (AOSs) are hotly pursued for advanced displays, flexible electronics, optoelectronics, and neuromorphic systems, the AOS Schottky barrier diodes (SBDs) have been tried only using the mainstream amorphous InGaZnO (a-IGZO) and the conservative bottom-anode structure. To deepen the study on AOS SBDs, the more challenging top-anode SBD is developed in this work using a versatile but vulnerable AOS, amorphous InZnO (a-IZO). Unsurprisingly, the Schottky interface defects are seriously increased by the top-anode process and the defective a-IZO, which cannot be effectively passivated using the incumbent oxidizing treatments. The hydrogenation is proposed to considerably suppress these annoying interface defects and thus correspondingly reduces the large leakage current, while the hydrogen doping easily deteriorates a-IGZO SBD. The underlying mechanism of such distinction is revealed to be the tricky interactions between defect and hydrogen in AOSs. Based on the sophisticated utilization of such defect-hydrogen interplay, the a-IZO/a-IGZO stack is hydrogenated together to simultaneously realize a high-conductivity bulk and low-defect interface, noticeably enhancing the performance metrics. Such top-anode SBD based on hydrogenated multilayer AOSs successfully blazes a novel evolution path for AOS SBDs. 

Defect‐Hydrogen Interactions in Top‐Anode Oxide Semiconductor Schottky Barrier Diode

Source-gated transistors are a new driver of low-power high-gain thin-film electronics. However, source-gated transistors based on organic semiconductors are not widely investigated yet despite their potential for future display and sensor technologies. We report on the fabrication and modeling of high-performance organic source-gated transistors utilizing a critical junction formed between indium-tin oxide and diketopyrrolopyrrole polymer. This partially blocked hole-injection interface is shown to offer both a sufficient level of drain currents and a strong depletion effect necessary for source pinch-off. As a result, our transistors exhibit a set of outstanding metrics, including an intrinsic gain of 160 V/V, an output resistance of 4.6 GΩ, and a saturation coefficient of 0.2 at an operating voltage of 5 V. Drift-diffusion simulation is employed to reproduce and rationalize the experimental data. The modeling reveals that the effective contact length is significantly reduced in an interdigitated electrode geometry, eventually contributing to the realization of low-voltage saturation.

High-Performance Organic Source-Gated Transistors Enabled by the Indium-Tin Oxide-Diketopyrrolopyrrole Polymer Interface.

Source-gated transistors (SGTs), which are typically realized by introducing a source barrier in staggered thin-film transistors (TFTs), exhibit many advantages over conventional TFTs, including ultrahigh gain, lower power consumption, higher bias stress stability, immunity to short-channel effects, and greater tolerance to geometric variations. These properties make SGTs promising candidates for readily fabricated displays, biomedical sensors, and wearable electronics for the Internet of Things, where low power dissipation, high performance, and efficient, low-cost manufacturability are essential. In this review, the general aspects of SGT structure, fabrication, and operation mechanisms are first discussed, followed by a detailed property comparison with conventional TFTs. Next, advances in high-performance SGTs based on silicon are first discussed, followed by recent advances in emerging metal oxides, organic semiconductors, and 2D materials, which are individually discussed, followed by promising applications that can be uniquely realized by SGTs and their circuitry. Lastly, this review concludes with challenges and outlook overview.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202101473

Huaiwu Zhang

Papers

New Opportunities for High-Performance Source-Gated Transistors Using Unconventional Materials