Transistor

A transistor comprising:

• a supporting substrate;
• an insulating layer provided on a major surface of the supporting substrate, the insulating layer having a first major surface and a second major surface that is in contact with the major surface of the supporting substrate;
• a semiconductor layer provided on the first major surface of the insulating layer, the semiconductor layer having a source portion, a drain portion of a first conductivity type, and a base region of a second conductivity type provided between the source portion and the drain portion;
• a gate insulating layer provided on the base region;
• a first gate electrode provided on the gate insulating layer;
• a second gate electrode provided on a surface of the supporting substrate, the surface being in the opposite side of the major surface of the supporting substrate;
• and
• a dielectric substance provided in a part of the supporting substrate, the dielectric substance being in contact with a portion in the second major surface of the insulating layer, the portion being opposed to the drain portion.

A transistor comprising:

• an insulating layer having a first major surface and a second major surface that is on the opposite side of the first major surface;
• a semiconductor layer provided on the first major surface of the insulating layer, the semiconductor layer having a source portion, a drain portion of a first conductivity type, and a base region of a second conductivity type provided between the source portion and the drain portion;
• a gate insulating layer provided on the base region;
• a first gate electrode provided on the gate insulating layer;
• and
• a second gate electrode provided not on a portion in the second major surface side of the insulating layer that is opposed to the drain portion but on a portion in the second major surface side of the insulating layer that is opposed to the base region.