To realize further progress in the field of integrated circuits, a high mobility channel material, such as InGaAs for n-MOSFETs, with a multi-gate structure is desired. To realize high current densities in InGaAs MOSFETs, heavily doped sources/drains obtained using epitaxial growth are required. Here, we report the regrowth of source/ drain using MOVPE for fin FET and nanosheet FET structures. A thinner flow liner for higher flow rate of 1.5 m/s was selected as a growth condition to improve the selective growth property and contact characteristics. As a result, a carrier concentration of 2 x 10(19) cm(-3) and contact resistivity of 8.0 x 10(-8) Omega cm(2) were obtained simultaneously. We fabricated fin FET and nanosheet structures as multi-gate MOSFETs. In the case of fin FETs, the surrounded growth of the channel and operation of a 16-nm-gate device were confirmed. In the case of nanosheet FETs, we used butt-jointed structures, i.e., we performed regrowth after the channel portion was formed into a mesa shape by etching, and the regrowth interface was a boundary between the channel and source/drain. After the regrowth and removal of the InP layer between the sheets, it was confirmed that the two layers of the nanosheets were supported by the regrown source/drain layers on both sides. In this structure, the operation of the 40-nm-gate device was also confirmed.