Abstract: A method of manufacturing a semiconductor element is provided as follows. A semiconductor layer that has a two-dimensional layered structure is formed on a substrate having a source region, a drain region, and a channel region. A high-k insulating layer is formed on the semiconductor layer by atomic layer deposition using trimethyl aluminum as a precursor and isopropyl alcohol as a reactant gas. A gate electrode is formed in the channel region on the high-k insulating layer. An insulating interlayer is formed on the gate electrode. Source and drain electrodes are formed in the source and drain regions on the insulating interlayer.