The research team at the Zhejiang University Hangzhou International Science and Technology Innovation Center has unveiled silicon-28 silane gas and 4-inch silicon-28 epitaxial wafers. This project is part of a national research initiative focused on the preparation and application of silicon-28 isotope epitaxial wafers, led by Yang Deren and Yu Linwei.
Silicon-28 is considered an ideal substrate for silicon-based quantum chips because its zero nuclear spin eliminates nuclear spin noise. Achieving high-abundance silicon-28 has historically been a significant challenge due to the similar chemical properties of silicon isotopes. This development marks the first time a domestic team has presented a complete material chain from gas to epitaxial substrate.
Testing by the National Institute of Metrology, China, confirmed that the silicon-28 silane gas achieved an isotope abundance of 99.99576% and a chemical purity of 99.99998%. These metrics are critical for the subsequent growth of high-abundance silicon-28 thin films, as they indicate minimal impurity levels and high isotope concentration.
The team utilized the specialized gas to produce 4-inch silicon-28 epitaxial wafers. Secondary ion mass spectrometry revealed an isotope abundance of 99.9937% in the epitaxial layer, demonstrating that the conversion process from gas to solid state maintains high isotopic integrity without significant dilution.
While these results represent a milestone in domestic material production for quantum computing, the team classifies the achievement as a phased breakthrough. Future research will focus on the performance of these materials in actual quantum devices, specifically regarding coherence time and gate fidelity, which require further validation beyond material purity.
