Mapping an on-chip terahertz antenna by a scanning near-field probe and a fixed field-effect transistor<xref ref-type="fn" rid="cpb140887fn1">*</xref>

Mapping an on-chip terahertz antenna by a scanning near-field probe and a fixed field-effect transistor*

Lü Li^a),^b), Sun Jian-Dong^a)†, Lewis Roger A.^c), Sun Yun-Fei^d), Wu Dong-Min^a),^d), Cai Yong^a), Qin Hua^a)‡

(a) Schematics of the experiment setup. The continuous-wave THz source is tuned at 875 GHz. (b) Zoom-in view of the near-field probing scheme by using a motorized vibrating probe. (c) Optical microscope images of the metallic probe and the tip. (d) Optical microscope image of the field-effect THz detector. The zoom-in box shows the central active region including three antenna blocks (A, B, C), the gate, and the two-dimensional electron gas (2DEG) channel. (e) The photocurrent ( i _t) tuned by the gate voltage ( V _G). (f) The THz beam profile probed by the detector scanned in the focal plane of OAP#2.