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Researchers Create World’s First Graphene Semiconductor

January 12, 2024 by Jake Hertz

Georgia Tech research could bring graphene's benefits for semiconductors in microelectronics. 

While graphene promises better efficiency and performance for electronics, material imitations have prevented anyone from translating its potential into a functional semiconductor—until now.

 

Graphene semiconductor.

Graphene semiconductor. Image used courtesy of Georgia Tech

 

In groundbreaking research at Georgia Tech, scientists created the world’s first successful graphene semiconductor.

 

Graphene: A Semimetal

Graphene has long been known as a material with exceptional electrical properties, including high electron mobility, excellent thermal conductivity, and remarkable mechanical strength. Its single-layer structure of carbon atoms arranged in a two-dimensional honeycomb lattice enables electrons to move through it with minimal resistance, making it one of the most conductive materials known.

However, despite its huge potential, other physical limitations have prevented its use in conventional semiconductor applications. 

 

Semimetals have no bandgap.

Semimetals have no bandgap. Image used courtesy of Lee et al.

 

In its inherent state, graphene is classified as a semimetal, meaning it does not naturally behave as a semiconductor or a metal. For a material to function effectively in electronic devices like transistors, it needs a bandgap so the material can be switched “on” and “off” through an electric field. This principle underpins the functioning of silicon-based electronics. Therefore, the principal challenge in leveraging graphene for electronic applications has been to induce this switchable characteristic, akin to silicon, without undermining its intrinsic properties.

 

Georgia Tech’s Graphene Research

Recently, a research team at Georgia Tech claimed to have created the world’s first graphene-based semiconductor device.

The researchers successfully showed that a well-annealed epigraphene on a specific silicon carbide crystal face can serve as a high-mobility 2D semiconductor. Specifically, the team developed semiconducting epigraphene (SEG) on single-crystal silicon carbide substrates, demonstrating a bandgap of 0.6 eV and room temperature mobilities exceeding 5000 cm²/Vs, which is significantly higher than silicon and other two-dimensional semiconductors​.

 

The SEG production process.

The SEG production process. Image used courtesy of Zhao et al.

 

The production of SEG involves a confinement-controlled sublimation (CCS) furnace where a semi-insulating SiC chip is annealed in a graphite crucible under an argon atmosphere. The temperature and rate of graphene formation are precisely controlled, with the silicon escape rate from the crucible playing a critical role. 

To characterize the SEG, the team used scanning tunneling microscopy (STM), scanning electron microscopy (SEM), low-energy electron diffraction (LEED), and Raman spectroscopy. These methods allowed for a detailed examination of SEG across multiple scales, distinguishing it from bare SiC and graphene and confirming its atomic registration with the SiC substrate​.

 

The Potential of Semiconducting Epigraphene

The research team underscores the potential of SEG in nanoelectronics. 

As a well-crystallized 2D semiconductor with a notable bandgap and high mobilities, SEG represents a major step forward for the industry in attaining the electrical benefits of materials like graphene. Future work will focus on reliably producing large terraces with suitable dielectrics, managing Schottky barriers, and developing integrated circuit schemes. Ultimately, the research team believes that SEG has the potential to become commercially viable and have a tangible impact on 2D nanoelectronics​.