The 4H-SiC VDMOSFET demonstrates a high reverse breakdown voltage (BV) due to the JFET region but experiences relatively high on-resistance (R_on). A widely adopted method to reduce the R_on is to uniformly increase the doping concentration of the JFET region, which results in a trade-off that reduces the BV. This study proposes a method to optimize the segmentation of the JFET region by selectively increasing the doping concentration using ‘total doping’, ‘half-doping’, and ‘quarter-doping’. The optimized quarter segment with a specific doping concentration slightly reduces BV, but the sharp decrease in specific on-resistance (R_on,sp) results in a 105% improvement in the performance index, Baliga’s Figure of Merit (BFOM). This research suggests the potential for electrically superior designs by modifying the doping concentration in the JFET region of conventional VDMOSFET structures.

Understanding the structure-property relationship in functional materials is crucial as microstructural features such as nano-precipitates, phase boundary, grain boundary segregation, and grain boundary phases play a key role in their functional properties. Atom probe tomography (APT) is an advanced analytical technique that allows for the three-dimensional (3D) mapping of atomic distributions and the precise determination of local chemical compositions in materials. Moreover, it offers sub-nanometer spatial resolution and chemical sensitivity at the tens of parts per million (ppm) level. Owing to its unique capabilities, this technique has been employed to uncover the 3D elemental distributions in a wide range of materials, including alloys, semiconductors, nanomaterials, and even biomaterials. In this paper, various kinds of examples are introduced for elucidating structure-property relationships on functional materials by utilizing the atom probe tomography.

Ni germanide (NiGe) is a promising alloy material with small contact resistance at the source/drain (S/D) of Ge MOSFETs. However, it is necessary to reduce the specific contact resistance between NiGe and the doped Ge S/D region in high-performance MOSFETs. In this study, a novel method is proposed to reduce the specific contact resistance between NiGe and p-type Ge (p-Ge) using a Tb interlayer. The specific contact resistance between NiGe and p-Ge was successfully decreased with the introduction of the Tb interlayer. To investigate the mechanism behind the reduction in the specific contact resistance, the elemental distribution and crystalline structure of NiGe were analyzed using secondary ion mass spectroscopy and X-ray diffraction. It is likely that the reduction in specific contact resistance was caused by an increase in the concentration of boron in the space between NiGe and p-Ge due to the influence of the Tb interlayer.