Semiconductor device

1. A semiconductor device that generates or detects terahertz waves, the semiconductor device comprising:

a substrate; and

a resonator configured to resonate the terahertz waves and provided on the substrate, the resonator comprising:

a semiconductor layer configured to have a gain of terahertz waves;

a first electrode configured to be connected to the semiconductor layer;

a second electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer and to be electrically connected to the semiconductor layer;

a third electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer, the semiconductor layer and the second electrode being arranged between the first electrode and the third electrode;

a conductor electrically connecting the second electrode to the third electrode, the conductor being arranged between the substrate and the third electrode; and

a dielectric layer configured to be arranged around the conductor, the semiconductor layer and the second electrode and between the first electrode and the third electrode and to be thicker than the semiconductor layer,

wherein a thickness of the conductor is greater than a thickness of the semiconductor layer,

wherein, in a plan view, an outline of the semiconductor layer is entirely included in an outline of the third electrode, and

wherein a greatest width of the conductor is 1/10 of an effective wavelength in the dielectric layer of the terahertz waves resonating in the resonator or less.

2. The semiconductor device according to claim 1 , wherein the conductor contains a material resistivity of which is 1×10 −6 Ω-m or less.

3. The semiconductor device according to claim 1 , wherein the conductor contains metal resistivity of which is 1×10 −6 Ω-m or less.

4. The semiconductor device according to claim 1 , wherein a width of a face of the conductor at the third electrode side is 20 times or less of a width of a face of the conductor at the second electrode side.

5. The semiconductor device according to claim 1 , wherein a width of a face of the conductor at the third electrode side is 10 times or less of a width of a face of the conductor at the second electrode side.

6. The semiconductor device according to claim 1 , wherein a width of the face of the conductor at the third electrode side is greater than or equal to a width of the face of the conductor at the second electrode side.

7. A semiconductor device, that generates or detects terahertz waves, the semiconductor device comprising:

a substrate; and

a resonator configured to resonate the terahertz waves and provided on the substrate, the resonator comprising:

a semiconductor layer configured to have a gain of terahertz waves;

a first electrode configured to be connected to the semiconductor layer;

a second electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer and to be electrically connected to the semiconductor layer;

a third electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer, the semiconductor layer and the second electrode being arranged between the first electrode and the third electrode;

a conductor electrically connecting the second electrode to the third electrode, the conductor being arranged between the substrate and the third electrode; and

a dielectric layer configured to be arranged around the conductor, the semiconductor layer and the second electrode and between the first electrode and the third electrode and to be thicker than the semiconductor layer,

wherein a thickness of the conductor is greater than a thickness of the semiconductor layer,

wherein, in a plan view, an outline of the semiconductor layer is entirely included in an outline of the third electrode, and

wherein a thickness of the conductor is greater than a thickness of the third electrode and is 1/10 or less of an effective wavelength in the dielectric layer of the resonating terahertz waves.

8. A semiconductor device that generates or detects terahertz waves, the semiconductor device comprising:

a substrate; and

a resonator configured to resonate the terahertz waves and provided on the substrate, the resonator comprising:

a semiconductor layer configured to have a gain of terahertz waves;

a first electrode configured to be connected to the semiconductor layer;

a second electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer and to be electrically connected to the semiconductor layer;

a third electrode configured to be arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer, the semiconductor layer and the second electrode being arranged between the first electrode and the third electrode;

a conductor electrically connecting the second electrode to the third electrode, the conductor being arranged between the substrate and the third electrode; and

a dielectric layer configured to be arranged around the conductor, the semiconductor layer and the second electrode and between the first electrode and the third electrode and to be thicker than the semiconductor layer,

wherein a thickness of the conductor is greater than a thickness of the semiconductor layer,

wherein, in a plan view, an outline of the semiconductor layer is entirely included in an outline of the third electrode, and

wherein a thickness of the dielectric layer is greater than the thickness of the semiconductor layer and is 1/10 or less of an effective wavelength in the dielectric layer of the resonating terahertz waves.

9. The semiconductor device according to claim 1 , wherein the semiconductor layer is ohmically connected to the second electrode.

10. The semiconductor device according to claim 1 , further comprising:

a fourth electrode configured to be arranged at the side at which the first electrode is arranged with respect to the semiconductor layer and to be electrically connected to the semiconductor layer,

wherein the dielectric layer includes a second conductor that electrically connects the first electrode to the fourth electrode and that is different from the conductor electrically connecting the second electrode to the third electrode.

11. The semiconductor device according to claim 10 , wherein the semiconductor layer is ohmically connected to the fourth electrode.

12. The semiconductor device according to claim 1 , wherein the semiconductor layer includes a resonant tunneling diode.

13. The semiconductor device according to claim 1 ,

wherein the resonator includes a patch antenna.

14. The semiconductor device according to claim 13 , further comprising:

a power supply configured to supply bias voltage to the semiconductor layer; and

a bias circuit configured to connect the resonator to the power supply,

wherein the bias circuit includes a strip line, a plug for connecting the strip line to the resonator, a decoupling capacitor and a shunt resistor that are connected to the strip line and that are connected in parallel to the semiconductor layer, a coplanar line connected to the power supply, and a converter that converts impedance of the strip line and impedance of the coplanar line.

15. The semiconductor device according to claim 14 , wherein the plug is arranged at a node of an electric field of the terahertz waves, which stands in the resonator.

16. The semiconductor device according to claim 1 , further comprising:

a bias circuit configured to supply bias voltage to the semiconductor layer; and

a line configured to connect the third electrode to the power supply.