Abstract: A transistor has a source electrode (22) on the opposite side of a semiconductor body layer (10) to a gate electrode (4) insulated from the body layer (10) by gate insulator (8). The source electrode (22) has a potential barrier to the semiconductor body layer (10), for example a Schottky barrier. At least one drain electrode (54) is also connected to the semiconductor body layer (10). A suitable source-drain voltage and gate voltage depletes the region of the semiconductor body layer adjacent to the source electrode (22), and then source-drain current is controlled by the gate voltage.