Semiconductor materials are used in cellphones, laptops, and all electronic equipment. Their unique characteristics make them indispensable for electronic devices, playing a vital role in our interconnected world.1,2
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Understanding Semiconductors
Semiconductors or integrated circuits are microelectronic devices made mostly of silicon or germanium. These chips, though tiny, comprise thousands of different components that work together to process information. The electrical conductivity of semiconductors can be altered by adding specific impurities or changing their temperature.3
Among the different types of semiconductor devices, logic chips, analog chips, memory chips, and optoelectronics dominate the market. The p-n junction, the primary type of semiconductor device, consists of N-type and P-type semiconductors forming a diode.
An imbalance is created, with one side being more positive. Electrons cross the junction toward the positive side, creating a central neutral part called the depletion junction.4
This region is vital as it directly affects electron movement. When an electric voltage is applied across a semiconductor device, the depletion region shrinks, allowing electrons to move in a specific direction.
Advancements in Materials
Gallium Carbide: The Future Material for Novel Semiconductors
Recent advancements in semiconductor materials have highlighted Gallium carbide (GaC) as a promising choice.
A recent study used Density Functional Theory (DFT) to explore the structural stability and electronic and optical properties of GaC, seeking novel third-generation semiconductors.
The study revealed that GaC, similar to gallium nitride (GaN), exists in three phases: two cubic phases and one hexagonal molecular configuration.5 The band gaps of these phases were found to be 0.449 eV, 2.733 eV, and 3.340 eV, respectively. Notably, the band gap of the cubic phase F4̅3m GaC and hexagonal GaC is larger than that of GaN.
Additionally, all three phases of GaC exhibited ultraviolet properties, and their first peak showed better migration compared to GaN. Thus, GaC shows potential as a third-generation semiconductor material for future industries.
Latest Innovations in Semiconductor Materials
The digital era revolution has been significantly influenced by advancements in inorganic semiconductors.
Recently, there has been a surge in interest in atomically thin 2D inorganic materials, particularly due to the global growth in graphene research. These materials have garnered significant attention for their potential applications in ultrathin, transparent, and flexible nanodevices.
A new method called the mixture precursor hot-injection colloidal route has been proposed to prepare Silver-Based Chalcogenide Semiconductor quantum dots. This method maintains a stable response even after multiple optical switching cycles, with a rise time of 2.11 seconds and a fall time of 1.04 seconds, indicating excellent optoelectronic performance.6
Among novel materials, semiconducting graphene stands out, particularly in graphene nano-electronics, due to its absence of an intrinsic bandgap. However, previous attempts to modify graphene's bandgap have been unsuccessful.
In a recent breakthrough, an international research team introduced the world's first functional semiconductor made from graphene, known as semiconducting epi-graphene (SEG).7 SEG is grown on single-crystal silicon carbide substrates and exhibits a band gap of 0.6 eV and room temperature mobilities exceeding 5,000 cm2 V-1 s-1.
This novel material boasts mobilities approximately ten times higher than silicon and twenty times higher than other two-dimensional semiconductors, making it pivotal for future semiconductor devices.8
In wearable electronics, researchers from Singapore have successfully created highly efficient semiconducting fibers that can be integrated into fabric and operated as smart wearable electronics.9 They developed a mechanical design and manufactured hair-thin, defect-free fibers spanning 100 meters, demonstrating their scalability. These fibers can be woven into fabrics utilizing existing methods.
To demonstrate their feasibility for real-life applications, the team created smart wearable electronics, including a beanie, sweater, and watch capable of detecting and processing signals. To broaden their applications, they plan to explore different materials for the fibers and develop semiconductors with various hollow core shapes, such as rectangular and triangular.
Innovations in Chip Design
The semiconductor industry has transformed, with new manufacturing methods boosting chip performance significantly.
One such concept gaining attention is the three-dimensional stacking of device layers, which has become increasingly important due to the challenges in scaling down devices.
A specific technique known as Monolithic 3D (M3D) integration has become popular. It involves forming an upper layer, an active semiconducting layer, and a lower layer of material. Compared to conventional 3D stacking techniques, this method leads to faster electron movement between layers and superior inter-layer connection density, boosting semiconductor performance.10
In M3D integration, traditional front-end-of-line and back-end-of-line processes can be employed to manufacture the lower device layer. However, materials compatible with the underlying layers should be used for the upper device layer, avoiding defects or strain on the lower layer devices.
In modern semiconductor manufacturing, constant research is underway to advance the multilevel interconnection technology that links the different metal layers. 3D Integrated Circuits (ICs) function efficiently only if the conducting layers are interconnected.
Researchers have developed an innovative multilevel metal interconnect scheme involving solvent-free patterning of insulator layers to create interconnecting areas, ensuring reliable electrical connections between metals in different layers.11
Using this technique, the team successfully fabricated the highest stacked organic transistors (a three-dimensional organic integrated circuit comprising five transistors and 20 metal layers) in a solvent-free manner. These transistors exhibit exceptional characteristics, including a high on/off current ratio of approximately 107, absence of hysteresis behavior, and outstanding device-to-device uniformity.
Fin Field-Effect Transistor Technology
Fin Field-Effect Transistors (FinFETs) technology has revolutionized the chip industry, with major companies investing heavily. Unlike conventional methods using a planar channel, FinFETs employ a fin-shaped channel standing vertically from the substrate.
This design offers superior control over transistor behavior, as the channel is surrounded by gate electrodes on three sides. The gate structure includes a gate oxide layer, a gate electrode, and a gate insulator.12 When a voltage is applied to the gate electrode, it creates an electric field in the channel region, controlling the flow of current through the channel.
The unique FinFET design allows better electrostatic control of the channel, reducing leakage current and enhancing overall transistor performance.
AI and Machine Learning in Semiconductor Chip Design
Advancements in high-throughput computation and materials databases have paved the way for data-driven machine learning methods in semiconductor design and manufacturing.13 Generative AI, in particular, aids in intricate semiconductor design.
Machine learning models are also used in materials discovery and chip design For example, supervised learning models uncover connections between semiconductor materials and their properties, enabling quick predictions of relevant properties for potential candidates. This accelerates the discovery of novel materials for superconducting applications.
Over time, these digital technologies will play a crucial role in semiconductor manufacturing and design, leading to novel innovations.
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References and Further Reading
[1] Growing Technology. (2024). Semiconductors: The Brains Behind Modern Electronics. [Online] Growing Technology. Available at: https://growingtechno.com/semiconductors-the-brains-behind-modern-electronics/
(Accessed on April 30 2024)
[2] Singh, Z. (2023). The Power of Semiconductor Materials Paving the Way for Technological Advancements. Advanced Materials Science Research. doi.org/10.37532/aaasmr.2023.6(4).67-69
[3] Singh, M., et al. (2023). Semiconductors and the Semiconductor Industry. [Online] Congressional Research Service. Available at: https://sgp.fas.org/crs/misc/R47508.pdf
(Accessed on April 30 2024)
[4] Ossila. (2024). How Do Semiconductors Work?. [Online] Ossila. Available at: https://www.ossila.com/pages/how-semiconductors-work#:~:text=How%20Do%20Semiconductors%20Work%3F,can%20be%20conductive%20or%20insulating (Accessed on April 30 2024)
[5] Pan, Y. (2024). Prediction of the Structural, Mechanical, and Physical Properties of GaC: As a Potential Third-Generation Semiconductor Material. Inorganic Chemistry. doi.org/10.1021/acs.inorgchem.4c00523
[6] Wang, S., et al. (2024). Advanced Inorganic Semiconductor Materials. Inorganics. doi.org/10.3390/inorganics12030081
[7] Beadle, A. (2024). Researchers Create World’s First Functional Semiconductor Made From Graphene. [Online] Technology Networks Applied Sciences. Available at: https://www.technologynetworks.com/applied-sciences/news/researchers-create-worlds-first-functional-semiconductor-made-from-graphene-382460
(Accessed on May 1 2024)
[8] Zhao, J., et al. (2024). Ultrahigh-mobility semiconducting epitaxial graphene on silicon carbide. Nature. doi.org/10.1038/s41586-023-06811-0
[9] Wang, Z., et al. (2024). High-quality semiconductor fibres via mechanical design. Nature. doi.org/10.1038/s41586-023-06946-0
[10] Nguyen, A., et al. (2024). Formation techniques for upper active channel in monolithic 3D integration: an overview. Nano Convergence. doi.org/10.1186/s40580-023-00411-4
[11] Yoo, H., et al. (2019). Highly stacked 3D organic integrated circuits with via-hole-less multilevel metal interconnects. Nat Commun. doi.org/10.1038/s41467-019-10412-9
[12] Anysilicon. (2023). FinFETs: The Ultimate Guide. [Online] Anysilicon. Available at: https://anysilicon.com/finfets-the-ultimate-guide/ (Accessed on May 1 2024)
[13] Yang, X., et al. (2024). Methods and applications of machine learning in computational design of optoelectronic semiconductors. Sci. China Mater. doi.org/10.1007/s40843-024-2851-9
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