Ten years of hard work to achieve mass production of 2-inch single-crystal diamond electronic devices
Author: Zhang Xingyong, Yan Tao
As a representative of the third-generation semiconductor materials, diamond semiconductors are also known as the ultimate semiconductors.
"Diamond semiconductors have material properties such as ultra-wide bandgap (5.45eV), high breakdown field strength (10MV/cm), high carrier saturation drift velocity, high thermal conductivity (22 W/cmK), and excellent device quality factor." Professor Wang Hongxing of Xi'an Jiaotong University introduced, "For this reason, the use of diamond substrates can be used to develop high-temperature, high-frequency, high-power, and radiation-resistant electronic devices, overcome the technical bottlenecks of the device's "self-heating effect" and "avalanche breakdown", and play an important role in the development of 5G/6G communications, microwave/millimeter wave integrated circuits, detection and sensing, etc."
However, the development of diamond electronic devices around the world is limited by the problem of large-size, high-quality single-crystal substrates.
"The commercialization of substrates such as silicon and sapphire provides the prerequisite for heteroepitaxial single-crystal diamond." Wang Hongxing said.
Recently, Professor Wang Hongxing's team at Xi'an Jiaotong University has successfully achieved mass production of 2-inch heteroepitaxial single crystal diamond self-supporting substrates using independent research and development technology.
10 years ago, my country's research and development in this area was almost blank. In 2013, Wang Hongxing, a national-level specially appointed expert introduced by Xi'an Jiaotong University, established the Xi'an Jiaotong University Wide Bandgap Semiconductor Materials and Devices Research Center and led the team of scientific researchers to tackle key problems. After 10 years of dedicated research and development, a series of technologies with independent intellectual property rights have been formed, including the research and development of diamond semiconductor epitaxial equipment, single crystal/polycrystalline substrate growth, and electronic device development, and 48 invention patents have been authorized.
"Large-size single crystal diamond production equipment and high-quality single crystal diamond substrate preparation technology are the key technologies we need to overcome in order to break the foreign blockade." Wang Hongxing said.
While Wang Hongxing led the team to research and develop key problems in the laboratory, he also carried out extensive cooperation with relevant large domestic communication companies and relevant research institutes of China Electronics Technology Group in the research and development and application of diamond semiconductor materials and devices, which promoted the practical development of diamond RF power electronic devices, power electronic devices, MEMS and other devices.
The team used microwave plasma chemical vapor deposition (MPCVD) technology to successfully achieve the batch production of 2-inch heteroepitaxial single crystal diamond self-supporting substrates, and effectively controlled the film uniformity, temperature field and flow field to improve the heteroepitaxial single crystal diamond yield. The substrate surface has a step-flow growth mode, which can reduce the defect density of the substrate and improve the crystal quality. The half-peak width of the XRD (004) and (311) rocking curves is less than 91arcsec and 111arcsec respectively. All indicators have surpassed the best foreign levels and reached the world's leading level.
It is understood that the single crystal diamond devices produced by this team have been widely used in my country's 5G communications and high-frequency and high-power detection device products.
