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Scientists have made significant progress in integrating diamonds into silicon chips by lowering the temperatures needed to grow them in the lab and combining the process with principles of quantum mechanics.
Diamonds are in high demand in electronics due to their unique crystalline structure, which allows them to withstand high electrical voltages and dissipate heat efficiently because they are non-conductive. However, their laboratory production requires extremely high temperatures, which are much higher than what chips can tolerate during their creation, making it difficult to integrate diamonds into chip technology. Lower temperatures, in turn, can degrade the quality of the diamond.
Uncovering the mystery surrounding diamonds
In a study published Sept. 13 in the journal Diamond and Related Materials, a team of scientists developed a method to lower the temperature needed to grow diamonds to the point that they can be used in the standard silicon manufacturing process. The discovery raises the possibility of creating faster, more energy-efficient diamond-based chips.
“To bring diamond into silicon manufacturing, we need to find a way to grow it at lower temperatures,” said lead author Yuri Barsukov, a research scientist at the Princeton Plasma Physics Laboratory (PPPL), in a statement. “This could open up new horizons for the silicon microelectronics industry.”
Diamonds are typically created using a method known as plasma-enhanced chemical vapor deposition, in which thin films of acetylene in a gaseous state are deposited onto a substrate as a solid.
Previous studies have shown that acetylene promotes diamond growth, but also produces soot that coats the diamond and interferes with its use in chips, sensors and optics, the team said. Scientists previously did not understand what determines whether acetylene turns into soot or diamond.
“We now know the answer,” Barsukov said in a statement. “Like water turning to ice, acetylene has a critical temperature for its phase change. Above this critical point, acetylene primarily promotes diamond formation, while at lower temperatures it leads to soot formation.”
The scientists found that the “critical temperature” depends on the concentration of acetylene and the presence of atomic hydrogen near the diamond's surface. Hydrogen atoms are not a direct source of diamond growth, but they are critical to stimulating its growth – even at much lower temperatures.
Quantum Diamond Protection
But that’s only one side of the equation. The way atoms bind together in diamond makes it ideal for quantum computing, secure communications, and high-precision sensors. So a study published July 11 in the journal Advanced Materials Interfaces looked at how to further prepare diamonds for use in sophisticated electronics. It focused on “quantum diamond” surfaces, where carbon atoms are removed and a neighboring atom is replaced with nitrogen, creating what scientists call “nitrogen-vacancy centers.” The researchers noted that the surface of these complex diamonds must be protected while keeping the nitrogen-vacancy centers intact.
“The electrons in this material don’t obey the laws of classical physics like heavier particles,” said Alastair Stacey, head of the Quantum Materials and Devices Unit at PPPL. “Instead, they behave according to the laws of quantum physics. But we can exploit these quantum mechanical properties by creating qubits,” he added. Qubits perform the same function in quantum computing as bits in traditional computing, enabling parallel computation.
“The advantage of qubits is that they can store much more information than regular bits,” Stacey explained. “This also means that they can give us much more data about the environment, making them extremely valuable in applications such as sensors.”
Scientists
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