Diamond is renowned for its exceptional hardness, high thermal conductivity, and low chemical reactivity. However, it exhibits low fracture toughness and poor electrical conductivity compared with many metallic materials and nonmetallic inorganic solids. For decades, it has been theorized that two-dimensional (2D) diamond may exhibit enhanced properties relative to bulk diamond because of its two-dimensional nature, including greater mechanical strength, extraordinary carrier mobility, and a tunable band gap.
Researchers from institutions in China successfully synthesized high-quality two-dimensional diamonds by heating graphene layers with a near-infrared (NIR) laser. They employed a high-pressure, high-temperature (HPHT) process to irreversibly transform graphene layers into 2D diamond. A polished rhenium (Re) metal foil was used as both the substrate and the laser-energy absorber to facilitate the heating process. The researchers succeeded in synthesizing 2D diamonds with thicknesses ranging from the equivalent of a graphene bilayer (~1 nm) to several hundred nanometers.
The 2D diamonds were characterized by Raman spectroscopy, whose spectra exhibited a well-defined characteristic peak at 1332 cm⁻¹ with a full width at half maximum (FWHM) of approximately 3.6 cm⁻¹, indicating their high crystalline quality. Photoluminescence measurements demonstrated that these diamonds are excellent candidates for quantum computing and sensing applications.
Furthermore, the researchers found that the band gap can be tuned within the range of 1.4 to 1.9 eV, depending on the proportion of sp³ species in the sample, which varied from 71.3% to 89.9%. Finally, they found that the diamonds remain stable at temperatures above 1000 °C.
This study demonstrates the successful synthesis of 2D diamond and reveals properties that differ from those of bulk (3D) diamond. The results indicate that 2D diamonds possess significant potential for applications in nanoelectronics and optoelectronics.
For further information go to nature communications
