Advances and challenges in single crystal diamond growth via microwave plasma chemical vapor deposition

This review comprehensively summarizes the latest developments in diamond semiconductor materials, emphasizing their outstanding attributes for high-power electronics. These include an ultra-wide bandgap of 5.47 eV, high electron/hole mobility of 4,000/3,800 cm2/(V·s), a breakdown electric field of 20 MV/cm, and a thermal conductivity of 22 W/cm·K. Despite the hurdles in n-type doping, recent progress in p-type Schottky barrier diodes (SBDs) and unipolar field-effect transistors (FETs) through terminal engineering has led to remarkable performances. These achievements encompass a breakdown voltage of 10 kV, a Baliga’s figure of merit of 874.6 MW/cm2, and a current density of 60 kA/cm2. Microwave plasma chemical vapor deposition (MPCVD) serves as the primary technique for industrial-scale synthesis of high-purity single-crystal diamond (SCD), enabling rapid deposition rates while outperforming polycrystalline diamond (PCD), high-pressure high-temperature (HPHT), and natural diamonds in electronic properties. The techniques of MPCVD homoepitaxy on diamond substrates and heteroepitaxy on foreign substrates are comprehensively examined. Homoepitaxy, capitalizing on the intrinsic properties of diamond, shows great promise for high-frequency applications, while heteroepitaxy holds potential for large-scale manufacturing. Through a balance of technical trade-offs, these methods can be harnessed to propel the development of diamond device fabrication roadmaps. This development will play a pivotal role in next-generation power electronics and quantum technologies. With the progress of MPCVD, research on diamond films has broadened applications by precisely controlling microstructures, morphologies, and surface properties. This overview concludes with an introduction to the most recent advancements, emerging applications, and persistent challenges in CVD diamond technology.