Recently, the entrepreneurial team led by Professor Wang Hongxing of Xi'an Jiaotong University has made significant progress and breakthroughs in the industrialization of single crystal diamond substrate technology. The team used a microwave plasma-based chemical vapor deposition (MPCVD) technology to achieve the mass production of 2-inch heteroepitaxial single crystal diamond substrates, which marks that China's research in the field of superhard materials has reached the international leading level, and will provide strong technical support for the development of related industries.

In the principle of semiconductor preparation, a substrate is a wafer made of semiconductor single crystal materials, and different substrate materials can produce semiconductor chips including single crystal diamond. Single-crystal diamond is known as the "ultimate semiconductor", and it is the same elemental semiconductor as silicon, and its performance completely surpasses that of existing semiconductors, and it can overcome the bottlenecks of "insufficient breakdown field strength" and "self-heating effect". Monocrystalline diamond has unique advantages in electronic devices with ultra-high voltage, ultra-high current, ultra-high power, high efficiency, radiation resistance and ultra-high frequency operation without cooling.

As an expert who has been engaged in the research of single crystal diamond wide bandgap semiconductor materials and devices for a long time in China, Wang Hongxing led the team to successfully realize the batch production of 2-inch heteroepitaxial single crystal diamond self-supporting substrates after long-term scientific research (as shown in Figure 1). Through the effective control of film uniformity, temperature field and flow field, the yield of heterotaxial single crystal diamond was improved. The substrate surface has a step-flow growth mode (as shown in Figure 2), which reduces the defect density of the substrate and improves the crystal quality. The half-peak widths of XRD(004) and (311) rocking curves are less than 91 arcsec and 111 arcsec, respectively (as shown in Fig. 3).

Figure 1: Photograph of a 2-inch heteroepitaxial single crystal diamond self-supporting substrate

Figure II. Heteroepitaxial diamond light microscopy photographs are (a) magnified 100x (b) magnified 500x

Figure 3. XRD test result (a)(004) surface swing curve; (b)(311) surface swing curve; (c)(311) plane quadruple symmetry; (d) Pole diagram

This method uses microwave plasma to excite the reactive gas to achieve the growth of heteroepitaxial single crystal diamond at lower temperatures and pressures. Compared to traditional preparation methods, this method has a higher growth rate and lower cost, while enabling large-scale production. In addition, it can effectively ensure the demand for high-quality, large-size electronic-grade single crystal diamond in the fields of domestic power electronic devices, thermal conductivity, radar detection, etc., and at the same time meet the demand for high-quality crystal seeds in scientific research in colleges and universities.

In addition to scientific applications, this breakthrough also has great potential in the commercial and industrial fields. For example, it may also be used in the following applications:

1. Advanced cutting tools: The high hardness and wear resistance of diamond make it an ideal material for manufacturing high-end cutting tools. By using heteroepitaxial single crystal diamond substrates, more durable and precise cutting tools can be manufactured, resulting in increased cutting efficiency and reduced production costs.

2. Electronic and semiconductor equipment: The thermal conductivity and electrical insulation of diamond make it an ideal material for electronic and semiconductor equipment. By using heteroepitaxial single crystal diamond substrates, more efficient and reliable electronic and semiconductor devices can be manufactured.

3. Optical instruments and lasers: The high optical transmittance and stability of diamond make it an ideal material for manufacturing optical instruments and lasers. By using heteroepitaxial single-crystal diamond substrates, more precise and stable optical instruments and lasers can be manufactured.

4. Sensors and detectors: The high sensitivity and stability of diamond make it an ideal material for manufacturing sensors and detectors. By using heteroepitaxial single crystal diamond substrates, more precise and reliable sensors and detectors can be manufactured.

It is worth mentioning that the industrialization of the research results has broken the monopoly of foreign technology, reduced the production cost of domestic related industries, and has broad application prospects. With the rapid development of emerging technologies such as 5G and the Internet of Things, the application demand for diamond in electronics, photonics, quantum and other fields is increasing. The mass production of heteroepitaxial single crystal diamond substrates will provide more stable and reliable raw material support for the development of related industries. At the same time, the promotion and application of this achievement will also drive the development of related industrial chains and promote the transformation and upgrading of China's economy.