Gated tunnel diode

A semiconductor device comprising a p region (2) and an n region (3) forming a p/n homojunction in a semiconductor layer (2, 3) formed between a semiconductor substrate (1) and a cap semiconductor layer (4) both of a wider band gap material than that of the semiconductor layer (2, 3). The p region (2) and the n region (3) are respectively provided with contact regions (6, 5), and a gate electrode (7) is formed on the cap layer (4). A tunneling current can flow between a two-dimensional electron gas (10) and a two-dimensional hole gas (11) induced at the heterojunction boundaries of the double heterojunction structure owing to an electric field applied to the semiconductor layer (2, 3). A buffer layer (71) of wide band gap semiconductor material can be further provided between the semiconductor substrate (1) and the semiconductor layer (2, 3) for reducing the leakage currents.