A horizontal surrounding gate MOSFET comprises a monolithic structure formed in an upper silicon layer of a semiconductor substrate which is essentially a silicon-on-insulator wafer, the monolithic structure comprising a source and drain portion oppositely disposed on either end of a cylindrical channel region longitudinally disposed between the source and drain. Portions of the boiler tubes, located at the top of the bank, are provided with spaced shields for protection from the fluid cleaning medium. The linear or branched alkyl group R preferably has a number of carbon atoms higher than or equal to 2 and lower than or equal to 12.