A semiconductor device, which is arranged in a semiconductor body (1), and which comprises at least one source region (4) and at least one drain region (5), each being of the first conductivity type, and at least one body (8) of the second conductivity type, arranged between source region (4) and drain region (5), and at least one gate electrode (10) which is isolated with respect to the semiconductor body (1) via an isolation layer (9). Said isolation layer (9) comprises polarizable particles, which are composed of a nanoparticulate isolating core and a sheath of polarizable anions or polarizable cations. The isolation layer (9) exhibits a high dielectric constant .epsilon..