Direct epitaxial growth of graphene on silicon carbide (SiC) stands as the most promising pathway for manufacturing wafer-scale, transfer-free graphene tailored for high-frequency electronics and augmented reality (AR) optical devices. However, the extreme temperatures required for silicon sublimation inevitably trigger violent atomic migration and step coalescence on the SiC surface, forming towering macro-steps tens of nanometers in height. These giant step bunches fracture graphene continuity, drive heterogeneous nucleation exclusively at step edges, and ultimately cause anisotropic electronic transport along versus across the step edges and elevated interfacial thermal resistance—all of which have remained intractable bottlenecks limiting epitaxial graphene device commercialization for decades.
A research team led by Professors Xiufang Chen, Huaying Ren, and Wancheng Yu at the Institute of Novel Semiconductors, Shandong University, has developed and optimized an innovative stepwise growth strategy that decouples buffer layer formation from subsequent graphene growth, addressing these long-standing challenges at their root. Their breakthrough findings are published in Nano Research on May 26.
Xiaocheng Jiang, the first author of the work, explained that the team initially observed a critical transition in the growth behavior of epitaxial graphene on SiC. “At sufficiently high temperatures, buffer layer formation and graphene growth occur simultaneously, leading to unstable surface evolution and giant step bunching. By identifying temperatures as the dominant factor governing this transition, we were able to design a growth pathway that decouples the two stages and stabilizes the surface morphology.”
"The key innovation of our approach is the deliberate separation of buffer layer formation from graphene growth," explained Professor Wancheng Yu, corresponding author of the paper. "By establishing a continuous buffer layer before graphene nucleation begins, we stabilize the SiC surface by blocking long-range silicon diffusion across terraces and create the conditions required for uniform graphene growth."
In the first stage, the SiC substrate is annealed under argon atmosphere to form a complete buffer layer that locks the surface morphology, eliminating the catastrophic giant step bunching that plagues conventional direct growth. In the second stage, the temperature is elevated to transform the pre-existing buffer layer into high-quality monolayer graphene, with a new buffer layer spontaneously forming beneath it. First-principles density functional theory (DFT) calculations validate the thermodynamic basis behind this strategy: the formation energy for lateral buffer layer expansion is 3–10 eV lower than that for vertical graphene nucleation in the initial growth phase, confirming a pronounced thermodynamic preference for the decoupled stepwise pathway. The team systematically investigated how first-stage temperatures (1350–1800°C) modulate buffer layer coverage and step topography, combining theoretical simulations with experimental data to define the precise temperature window for effective process decoupling.
"The pre-formed buffer layer completely rewrites the growth kinetics landscape," added Professor Huaying Ren, another corresponding author. "It equalizes chemical reactivity between step edges and terraces, enabling homogeneous nucleation across the entire substrate surface rather than just at step edges. This shift drives the system closer to near-equilibrium growth conditions, suppresses step bunching, and enables the reproducible fabrication of large-area, uniform, single-crystal monolayer graphene."
The team successfully scaled this process to 6-inch SiC wafers, achieving exceptional structural uniformity across the full wafer surface. By dramatically improving tolerance to SiC substrate miscut angles—a critical parameter for wafer-scale manufacturing—the stepwise growth strategy substantially broadens the process window for epitaxial graphene production and enhances its industrial scalability.
These advances establish a practical route toward the monolithic integration of high-quality graphene with SiC-based electronics, power devices, and optoelectronic systems, including emerging applications such as next-generation AR waveguides. Beyond its technological implications, the work also advances the fundamental understanding of buffer layer-mediated kinetic control in SiC epitaxy, providing new insights into interface-engineered growth of two-dimensional materials on semiconductor platforms.
Other contributors of the paper include Xiaocheng Jiang, Yunye Wang, Ting Cheng, Qinghe Wang, Can Liu, Jiaqi Jiang, Bin Gao, Xiucai Sun, Li Sun, Qiang Dong, Kaihui Liu, and Xiangang Xu.
This work was supported by the Shandong Province Key Research and Development Program (Grant No. 2025CXPT203), the National Natural Science Foundation of China (Grant No. U23A20569), and the Shandong Provincial Natural Science Foundation (Grant No. ZR2025MS754).
DOI Link:
https://doi.org/10.26599/NR.2026.94908882
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
Nano Research
Stepwise growth of graphene on silicon carbide: decoupling buffer layer formation from graphene growth
26-May-2026