2024-03-27 09:18:57
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Among all known semiconductors, diamond significantly surpasses the traditional semiconductor silicon with its excellent quality factor, providing a promising material choice for the next generation of electronic devices. However, for diamond to be used in integrated circuit fabrication, diamond complementary metal oxide semiconductor (CMOS) devices must be developed with n-channel and p-channel conductivity, the same device construction principles we have established for the semiconductor silicon . Unfortunately, due to technical difficulties in n-channel metal oxide semiconductor field effect transistors (MOSFETs), the research and development of diamond CMOS has not been able to achieve a breakthrough.

Recently, researchers at Japan's National Institute of Materials Science (NIMS) have made breakthrough progress. Based on the step flow nucleation mode, they successfully fabricated an electronically graded phosphorus-doped n-type diamond epitaxial layer with an atomically flat surface and demonstrated an n-channel diamond MOSFET. This n-type diamond MOSFET exhibits a field-effect mobility of approximately 150 cm²/V·s at 573 K, which ranks first among all n-channel MOSFETs based on wide-bandgap semiconductors. This major achievement not only helps promote the research and development of diamond CMOS integrated circuits, but also opens up new paths in the development of energy-saving and highly reliable electronic devices, integrated spin electronics and extreme sensors, especially in harsh environments. It shows great potential in applications requiring high-power electronic devices.


Figure 1. High-quality lightly phosphorus-doped n-type diamond epitaxial layer.



1. The NIMS research team developed the world's first n-channel diamond MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The developed n-channel diamond MOSFET is a key step in the development of CMOS (complementary metal oxide semiconductor: one of the most popular technologies in computer chips) integrated circuits and diamond power electronics for harsh environment applications.
2. Semiconductor diamond has excellent physical properties such as ultra-wide bandgap energy of 5.5eV, high carrier mobility, and high thermal conductivity. It has high performance and high reliability application prospects in extreme environmental conditions such as high temperature and high radiation. horizontal (e.g., near a nuclear reactor core). By using diamond electronics, not only are the thermal management needs of traditional semiconductors alleviated, but these devices are also more energy efficient and can withstand higher breakdown voltages and harsh environments. On the other hand, with the development of diamond growth technology, power electronics, spin electronics, and microelectromechanical systems (MEMS) sensors that can operate under high temperature and strong radiation conditions, there is a constant demand for peripheral circuits based on diamond CMOS devices. Increase. Integration. For the fabrication of CMOS integrated circuits, as with conventional silicon electronics, p- and n-channel MOSFETs are required. However, n-channel diamond MOSFETs have not yet been developed.

3. The NIMS research team developed a technology to grow high-quality single-crystal n-type diamond semiconductors with smooth and flat platforms at the atomic level by doping diamond with low concentrations of phosphorus. Using this technology, the team successfully manufactured n-channel diamond MOSFETs for the first time in the world. The MOSFET is mainly composed of an n-channel diamond semiconductor layer and another diamond layer doped with a high concentration of phosphorus. The use of the latter diamond layer significantly reduces source and drain contact resistance. The team confirmed that the diamond MOSFETs produced actually functioned as N-channel transistors. In addition, the team also verified the excellent high-temperature performance of the MOSFET, with its field-effect mobility, an important performance indicator of transistors, of approximately 150 cm2/V・sec at 300°C.
4. These results are expected to facilitate the development of CMOS integrated circuits for manufacturing energy-saving power electronics, spintronics, and (MEMS) sensors in harsh environments.


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