Terahertz transceiver including triple-barrier resonant tunneling diode

1 . A terahertz (THz) transceiver, comprising:

a triple-barrier resonant tunneling diode (TBRTD) with an emitter layer and a collector layer;

a resonator antenna electrically connected to the emitter layer and the collector layer of the TBRTD;

a spacer layer disposed on the resonator antenna; and

a radiator antenna disposed on the spacer layer,

wherein the spacer layer separates the resonator antenna and the radiator antenna, and

wherein the resonator antenna and the radiator antenna are vertically aligned and inductively coupled.

2 . The THz transceiver according to claim 1 , wherein:

in a transmitter operation, the TBRTD generates a first THz current, the resonator antenna creates resonance with the TBRTD based on the first THz current to generate a THz electromagnetic wave, and the THz electromagnetic wave inductively couples with the radiator antenna and is emitted into a free space by the radiator antenna; and

in a receiver operation, the radiator antenna absorbs an incident THz signal, an electromagnetic field of the incident THz signal at the radiator antenna inductively couples with the resonator antenna, and the electromagnetic field at the resonator antenna causes a second THz current flow through the TBRTD due to electrical rectification.

3 . The THz transceiver according to claim 1 , wherein the resonator antenna and the radiator antenna are fractal antennas shaped according to a same fractal curve or a same fractal pattern.

4 . The THz transceiver according to claim 3 , wherein:

at least one of the resonator antenna and the radiator antenna comprises at least one switch embedded in the fractal curve or the fractal pattern of the resonator antenna and/or the radiator antenna; and

the at least one switch is configured for connecting and disconnecting parts of the resonator antenna and/or the radiator antenna to shift an operating frequency of the resonator antenna and/or the radiator antenna.

5 . The THz transceiver according to claim 1 , wherein the TBRTD comprises a collector barrier, a collector well disposed on the collector barrier, a main barrier disposed on the collector well, an emitter well disposed on the main barrier, and an emitter barrier disposed on the emitter well.

6 . The THz transceiver according to claim 5 , wherein:

the main barrier is made of In0.52Al0.48As;

the collector well and the emitter well are made of In0.53Ga0.47As; and

the collector barrier and the emitter barrier are made of AlAs.

7 . The THz transceiver according to claim 5 , wherein:

a thickness of the emitter well is larger than a thickness of the collector well;

the thickness of the collector well is larger than a thickness of the main barrier;

the collector barrier and the emitter barrier have a same thickness; and

the thickness of the main barrier is larger than the same thickness of the collector barrier and the emitter barrier.

8 . The THz transceiver according to claim 1 , further comprising:

a substrate made of indium phosphide;

a buffer layer made of In0.53Ga0.47As and disposed on the substrate; and

a passivation layer made of silicon dioxide or polymer and disposed on the buffer layer, wherein the TBRTD is embedded in the passivation layer, and

wherein the spacer layer is made of polymer and disposed on the passivation layer.

9 . The THz transceiver according to claim 8 , further comprising:

a bottom contact layer made of In0.53Ga0.47As and disposed between the buffer layer and the TBRTD; and

a top contact layer made of In0.53Ga0.47As and disposed between the TBRTD and the spacer layer, wherein,

a common doping concentration of silicon in the bottom contact layer and the top contact layer is larger than a common doping concentration of silicon in the collector layer and the emitter layer of the TBRTD; and

the common doping concentration of silicon in the collector layer and the emitter layer of the TBRTD is larger than a doping concentration of silicon in the buffer layer.

10 . The THz transceiver according to claim 8 , wherein:

the radiator antenna has a same shape and a same size as those of a main section of the resonator antenna; and

the main section of the resonator antenna is disposed on the substrate, the buffer layer or the passivation layer.

11 . The THz transceiver according to claim 8 , further comprising:

a grating reflector disposed under the substrate and made of interleaved metal and dielectric,

wherein a combined width of each adjacent pair of a piece of metal and a piece of dielectric in the grating reflector is smaller than a wavelength of a THz electromagnetic wave generated from the resonator antenna.

12 . The THz transceiver according to claim 8 , wherein

at least one of the substrate, the buffer layer, the passivation layer and the spacer layer comprises a ferroelectric material, and

a permittivity of the ferroelectric material changes when an electric field applied to the ferroelectric material changes.

13 . A method of fabricating a terahertz (THz) transceiver, comprising:

forming a triple-barrier resonant tunneling diode (TBRTD) with an emitter layer and a collector layer,

forming a resonator antenna electrically connected to the emitter layer and the collector layer of the TBRTD;

forming a spacer layer disposed on the resonator antenna; and

forming a radiator antenna disposed on the spacer layer,

wherein the spacer layer separates the resonator antenna and the radiator antenna, and

wherein the resonator antenna and the radiator antenna are vertically aligned and inductively coupled.

14 . The method according to claim 13 , wherein the resonator antenna and the radiator antenna are fractal antennas shaped according to a same fractal curve or a same fractal pattern.

15 . The method according to claim 13 , wherein the TBRTD comprises a collector barrier, a collector well disposed on the collector barrier, a main barrier disposed on the collector well, an emitter well disposed on the main barrier, and an emitter barrier disposed on the emitter well.

16 . The method according to claim 15 , wherein:

the main barrier is made of In0.52Al0.48As;

the collector well and the emitter well are made of In0.53Ga0.47As; and

the collector barrier and the emitter barrier are made of AlAs.

17 . The method according to claim 15 , wherein:

a thickness of the emitter well is larger than a thickness of the collector well;

the thickness of the collector well is larger than a thickness of the main barrier;

the collector barrier and the emitter barrier have a same thickness; and

the thickness of the main barrier is larger than the same thickness of the collector barrier and the emitter barrier.

18 . The method according to claim 13 , further comprising:

forming a grating reflector disposed under the resonator antenna and made of interleaved metal and dielectric,

wherein a combined width of each adjacent pair of a piece of metal and a piece of dielectric in the grating reflector is smaller than a wavelength of a THz electromagnetic wave generated from the resonator antenna.

19 . The method according to claim 13 , further comprising:

providing a ferroelectric material disposed under the resonator antenna or the radiator antenna,

wherein a permittivity of the ferroelectric material changes when an electric field applied to the ferroelectric material changes.

20 . The method according to claim 13 , further comprising:

forming a first conductor layer;

forming a polymer dispersed liquid crystal (PDLC) layer on the first conductor layer;

forming a second conductor layer on the PDLC layer;

forming an aluminum layer on the second conductor layer;

forming a photoresist layer on the aluminum layer;

forming a fractal pattern in the photoresist layer, the aluminum layer, the second conductor layer, the PDLC layer and the first conductor layer by photolithography and etching; and

removing the photoresist layer and the aluminum layer,

wherein the first conductor layer and the second conductor layer constitute the resonator antenna and/or the radiator antenna.