Terahertz device and fabrication method of the same

1. A terahertz device comprising:

a semiconductor substrate;

a first semiconductor layer disposed on the semiconductor substrate;

an active element formed by being laminated on the first semiconductor layer;

a second electrode connected to the first semiconductor layer so as to be connected to one side of a main electrode of the active element, the second electrode disposed on the semiconductor substrate;

a first electrode connected to another side of the main electrode of the active element, the first electrode disposed on the semiconductor substrate so as to be opposite to the second electrode; and

a rear reflector metal layer disposed on aback side surface of the semiconductor substrate opposite to the first semiconductor layer, wherein

the active element forms a resonator between the second electrode and the first electrode, wherein

electromagnetic waves are reflected on the rear reflector metal layer, and electromagnetic waves have a surface light-emission radiating pattern or surface light-receiving pattern in a vertical direction with respect to the semiconductor substrate.

2. The terahertz device according to claim 1 , wherein

a distance between the active element and a front side surface of the rear reflector metal layer contacted with the semiconductor substrate is ¼ times as long as wavelength λ.

3. The terahertz device according to claim 1 , wherein

the first electrode and the second electrode comprise a dipole antenna.

4. The terahertz device according to claim 3 , further comprising:

a first feed line and a second feed line each which is connected to the dipole antenna; and

a first pad electrode and a second pad electrode respectively connected to the first feed line and the second feed line.

5. The terahertz device according to claim 4 , further comprising

an MIM reflector connected between the first pad electrode and the second pad electrode.

6. The terahertz device according to claim 1 , further comprising:

a resistance element connected between the first electrode and the second electrode.

7. The terahertz device according to claim 6 , wherein

the resistance element comprises metallic wiring.

8. The terahertz device according to claim 7 , wherein

the metallic wiring comprises one selected from the group consisting of Bi, Ni, Ti, and Pt.

9. The terahertz device according to claim 1 , wherein

the active element is arranged as multichip implementation.

10. The terahertz device according to claim 9 , wherein

the active element is arranged as cell array implementation.

11. The terahertz device according to claim 1 , wherein

the active element is one selected from the group consisting of a resonant tunneling diode, a TUNNETT diode, an IMPATT diode, a GaAs based field-effect transistor, a GaN based FET, a high electron mobility transistor, and a hetero-junction bipolar transistor.

12. A terahertz device comprising:

a semiconductor substrate;

a first semiconductor layer disposed on the semiconductor substrate;

a first cathode region and a second cathode region formed by patterning the first semiconductor layer;

a first resonant tunneling diode of which a first cathode is connected to the first cathode region, and a first anode is connected to the second cathode region;

a second resonant tunneling diode of which a second cathode is connected to the second cathode region, and a second anode is connected to the first cathode region; and

a rear reflector metal layer disposed on aback side surface of the semiconductor substrate opposite to the first semiconductor layer, wherein

when the first resonant tunneling diode is biased to a negative-resistance oscillation state, the second resonant tunneling diode is biased to a resistance state, wherein

electromagnetic waves are reflected on the rear reflector metal layer, and electromagnetic waves have a surface light-emission radiating pattern or surface light-receiving pattern in a vertical direction with respect to the semiconductor substrate.

13. The terahertz device according to claim 12 , further comprising:

a first cathode electrode disposed on the first cathode region;

a second cathode electrode disposed on the second cathode region;

a first anode electrode connected to the first anode; and

a second anode electrode connected to the second anode, wherein

the first cathode electrode is commonly connected with the second anode electrode, and the second cathode electrode is commonly connected with the first anode electrode.

14. The terahertz device according to claim 12 , wherein

the first resonant tunneling diode and the second resonant tunneling diode respectively comprise:

quantum well layers;

second spacer layers disposed at an anode side via tunnel barrier layers respectively sandwiching the quantum well layers; and

first spacer layers disposed at a cathode side, wherein

a thickness of the first spacer layer and a thickness of the second spacer layer is different from each other.

15. The terahertz device according to claim 12 , wherein

a thickness of the first spacer layer in the first resonant tunneling diode and a thickness of the first spacer layer in the second resonant tunneling diode are different from each other.

16. The terahertz device according to claim 12 , wherein

a thickness of the second spacer layer in the first resonant tunneling diode and a thickness of the second spacer layer in the second resonant tunneling diode are different from each other.

17. The terahertz device according to claim 12 , further comprising

dipole antennas respectively connected to the first cathode and the second cathode.

18. The terahertz device according to claim 17 , further comprising:

feed lines respectively connected to the dipole antennas; and

pad electrodes respectively connected to the feed lines.

19. The terahertz device according to claim 12 , further comprising

an MIM reflector connected between the first cathode and the second cathode.

20. A fabrication method of a terahertz device comprising:

forming a first semiconductor layer on a semiconductor substrate;

patterning the first semiconductor layer so as to form a first cathode region and a second cathode region;

forming a first resonant tunneling diode of which a first cathode is connected to the first cathode region and a first anode is connected to the second cathode region;

forming a second resonant tunneling diode of which a second cathode is connected to the second cathode region and a second anode is connected to the first cathode region;

forming a first cathode electrode on the first cathode region, the first cathode electrode commonly connected with a second anode electrode;

forming a second cathode electrode on the second cathode region, the second cathode electrode commonly connected with a first anode electrode; and

forming a rear reflector metal layer on a back side surface of the semiconductor substrate opposite to the first semiconductor layer.

21. The fabrication method of a terahertz device according to claim 20 , wherein the steps of forming the first resonant tunneling diode and the second resonant tunneling diode comprise:

forming first spacer layers on the first semiconductor layer;

forming first tunnel barrier layers respectively on the first spacer layers;

forming quantum well layers respectively on the first tunnel barrier layers;

forming second tunnel barrier layers respectively on the quantum well layers; and

forming second spacer layers respectively on the second tunnel barrier layer, the thicknesses second spacer layers being respectively different from the thicknesses of the first spacer layers.