Natsuo Tatsumi

Recent Progress of Diamond Device toward Power Application

Diamond is nominated as a material candidate for future high power device due to its superior material properties and resulting very high FOM. In this paper, our recent progresses and the expected possibilities of diamond for power electronics applications are introduced as short review. Firstly for the epitaxial growth, by adopting step-flow epitaxial growth by off- angle substrate with optimized growth conditions, we have succeeded in reducing these killer defects almost six orders from 106cm-2 to almost 100cm-2 levels. For the substrate, our recently developed technology to fabricate diamond plates from bulk, 12x13mm2 size are available to use, that can avoid fabrication difficulties with small size substrate. Secondly for the device, primitive studies showed possibly for the advantage of diamond such as low reverse leakage current, high temperature and high current density operation.

Device Characteristics Dependence on Diamond SDBs Area

Device size scaling of pseudo-vertical diamond Schottky barrier diodes (SBDs) has been characterized for high-power device applications based on the control of doping concentration and thickness of the p- CVD diamond layer. Decreasing parasitic resistance on the p+ layer utilizing lithography and etching makes possible to get a constant specific on-resistance of less than 20 mOhm-cm2 with increasing device size up to 200 µm. However, the leakage current under low reverse bias conditions is increased markedly. Due to the increase in the leakage current, the reverse operation limit is decreased from 2.4 to 1.3 MV/cm when the device size is increased from 30 to 150 µm. If defects induce an increase in leakage current under the reverse conditions, the density of the defects can be estimated to be 104–105/cm2. This value is 5–10 times larger than the density of dislocations in single crystal diamond substrate.