Field-effect Self-mixing Terahertz Detectors

A comprehensive device model considering both spatialdistributions of the terahertz field and the field-effect self-mixing factorhas been constructed for the first time in the thesis. The author has foundthat it is the strongly localized terahertz field induced in a small fractionof the gated electron channel that plays an important role in the highresponsivity. An AlGaN/GaN-based high-electron-mobility transistor with a2-micron-sized gate and integrated dipole antennas has been developed and canoffer a noise-equivalent power as low as 40 pW/Hz1/2 at 900 GHz. By furtherreducing the gate length down to 0.2 micron, a noise-equivalent power of 6pW/Hz1/2 has been achieved. This thesis provides detailed experimentaltechniques anddevice simulation for revealing the self-mixing mechanismincluding a scanning probe technique for evaluating the effectiveness ofterahertz antennas. As such, the thesis could be served as a valuableintroduction towards further development of high-sensitivity field-effect terahertzdetectors for practical applications.