Semiconductor element
A semiconductor element comprising: an antenna array that is provided with a plurality of antennas each including a semiconductor layer having an electromagnetic wave gain or carrier nonlinearity with respect to a terahertz wave; and a coupling line that synchronizes adjacent antennas in the antenna array with each other at a frequency of the terahertz wave, wherein the coupling line includes a plurality of first regions connected to the adjacent antennas respectively and a second region provided between the plurality of first regions, wherein the second region has impedance different from impedance of each of the first regions, and wherein the second region has a loss larger than a loss of the individual first region at a frequency other than a resonance frequency of the antenna array.
1. A semiconductor element comprising:
an antenna array that is provided with a plurality of antennas each including a semiconductor layer having an electromagnetic wave gain or carrier nonlinearity with respect to a terahertz wave; and
a coupling line that synchronizes adjacent antennas in the antenna array with each other at a frequency of the terahertz wave,
wherein the coupling line includes a plurality of first regions connected to the adjacent antennas respectively and a second region provided between the plurality of first regions,
wherein the second region has impedance different from impedance of each of the first regions, and
wherein the second region has a loss larger than a loss of each individual first region at a frequency other than a resonance frequency of the antenna array.
2. The semiconductor element according to claim 1 , wherein the plurality of antennas each include
a substrate,
a first conductor layer laminated on the substrate,
the semiconductor layer electrically connected to the first conductor layer,
a second conductor layer electrically connected to the semiconductor layer and faces the first conductor layer, and
a dielectric layer formed between the first conductor layer and the second conductor layer.
3. The semiconductor element according to claim 2 , further comprising a third conductor layer,
wherein the coupling line has a structure in which the dielectric layer is sandwiched between the third conductor layer and the first conductor layer.
4. The semiconductor element according to claim 3 , wherein the third conductor layer in the second region has resistance higher than resistance of the third conductor layer in the first region.
5. The semiconductor element according to claim 3 , wherein the third conductor layer in the second region has resistivity higher than resistivity of the third conductor layer in the first region.
6. The semiconductor element according to claim 3 , wherein the third conductor layer in the second region has a width smaller than a width of the third conductor layer in the first region.
7. The semiconductor element according to claim 3 , wherein the third conductor layer in the second region has a thickness smaller than a thickness of the third conductor layer in the first region.
8. The semiconductor element according to claim 1 , wherein the second region includes a structure having capacitance higher than capacitance of the first region.
9. The semiconductor element according to claim 1 , wherein the second region includes a structure having impedance lower than impedance of the first region.
10. The semiconductor element according to claim 2 ,
wherein the dielectric layer includes a second dielectric in the second region and a first dielectric in the first region, and
wherein the second dielectric is made of a material having a loss larger than a loss of the first dielectric at a high frequency.
11. The semiconductor element according to claim 2 ,
wherein the dielectric layer includes a second dielectric in the second region and a first dielectric in the first region, and
wherein the second dielectric has a layer thickness smaller than a layer thickness of the first dielectric.
12. The semiconductor element according to claim 1 , wherein the second region is disposed at an antinode of an electric field of the terahertz wave having a resonance frequency in the coupling line.
13. The semiconductor element according to claim 1 , wherein the antenna array and the coupling line are formed on the same substrate.
14. The semiconductor element according to claim 1 , wherein each of the antennas is a patch antenna.
15. The semiconductor element according to claim 1 , wherein the coupling line is a microstrip line.
16. The semiconductor element according to claim 1 , wherein the semiconductor layer includes a negative resistance semiconductor element.
17. The semiconductor element according to claim 16 , wherein the negative resistance semiconductor element is a resonant tunneling diode.
18. The semiconductor element according to claim 1 , wherein
the coupling line is connected to a shunt element connected in parallel with each of the semiconductor layers of the adjacent antennas, and
the shunt element is connected to a node of the electric field of the terahertz wave having the resonance frequency in the coupling line.
19. The semiconductor element according to claim 1 , wherein the plurality of antennas are each connected to a bias circuit including a power supply that supplies a bias signal to the semiconductor layer.
20. The semiconductor element according to claim 1 , wherein the terahertz wave is an electromagnetic wave in a frequency range of at least 30 GHz and not more than 30 THz.