Development of diamond-based power devices

Abstract

-Verification of its superiority as the ultimate power device-Diamond is expected to be an excellent material exceeding SiC for producing low loss power devices because of its superior material characteristics. We have developed series of elemental technologies including killer-defect free epitaxial growth, refractory Schottky contact, Schottky barrier height control associated with low leakage current and termination structure. As a result, we have developed a refractory Schottky barrier diode with fast switching capability, which can operate for over 300,000 hours at 250 °C. R&D of large scale wafers and large power devices are required to realize low-loss devices with a new concept of "cooling system free." Development of diamond-based power devicesKeywords : Diamond, power switching device, refractory, low loss, Schottky diode − 148 −

Surface Morphology and Microstructure Evolution of Single Crystal Diamond during Different Homoepitaxial Growth Stages

“…The cubic diamond crystals were composed of (001) and (111) faces, and the smooth square portions were (001) faces. As deposition time ran, the pyramidal hillocks significantly grew and resulted in the merging of adjacent pyramids and the generation of steps, and the (001) faces were formed on the top of the square pyramidal crystals (Figure 1b) by lateral growth in the [110] and [1][2][3][4][5][6][7][8][9][10] directions, leading to a change of surface morphologies from hillocks to macro-steps. When the deposition time of step-flow growth was extended to 20 min, as shown in Figure 1d, the macro-steps appeared while the isolated cubic diamond crystals disappeared.…”

“…Due to its excellent electrical properties, such as wide band-gap, high carrier mobility, high saturation velocity, low dielectric constant, and high breakdown field, diamond is considered as a potential candidate material for fabrication of durable diamond-based devices with high performances of high-frequency and high-power, which can operate in harsh environments [1][2][3][4][5]. Furthermore, diamond possesses the highest thermal conductivity among materials, higher than GaN and SiC, and is the most ideal heat spreading material for power devices.…”

Microscopic Evaluation of Al₂O₃/p-Type Diamond (111) Interfaces Using Scanning Nonlinear Dielectric Microscopy

“…Because diamond possesses a high breakdown electric field, high thermal conductivity, and high carrier mobility, it has a potential to realize the power devices with high breakdown voltage, high power, and high-speed operation [1][2][3]. Recently, inversion type p-channel MOSFETs with normally off characteristics have been fabricated using a P-doped and OH-terminated diamond body on a diamond (111) substrate with an atomic layer deposited (ALD) Al2O3 dielectric [4].…”

Fast removal of surface damage layer from single crystal diamond by using chemical etching in molten KCl + KOH solution

“…In recent years, diamond has attracted increasing attention as one of the most promising wide bandgap semiconductors for fabricating next-generation power devices that are more energy-efficient and can work at high temperature and in harsh environments [1,2]. N-or p-type epitaxial layers, which power devices are fabricated in, require the planarization of diamond single crystal for substrate usage [3,4].…”