Patent ID: 8304812

Claim:
A terahertz wave radiating element, comprising: a first nitride semiconductor layer formed on a substrate; a second nitride semiconductor layer formed over the first nitride semiconductor layer, and having a wider bandgap than the first nitride semiconductor layer; and a gate electrode formed on the second nitride semiconductor layer, and source and drain electrodes formed on the second nitride semiconductor layer so as to face each other with the gate electrode interposed therebetween, wherein: each of the source and drain electrodes is formed by a plurality of ohmic fingers that are arranged periodically, a plasma wave of a two-dimensional electron gas that is generated at a heterojunction with the second nitride semiconductor layer in the first nitride semiconductor layer is converted to a radiation field, and a period “Λ” with which the plurality of ohmic fingers are periodically arranged satisfies a relation of “Λ=ms/f,” where “s” represents a velocity of the plasma wave, “f” represents a frequency of the radiation field, and “m” is a natural number.