Fermi-Level Managed Barrier Diode: Room-Temperature Low-Noise Terahertz-Wave Detector

We present our recent results on Fermi-level managed barrier (FMB) diodes for sensitive THz-wave detection at room temperature. The FMB diode has a very low barrier height, which is the key for achieving low noise characteristics under a zero-biased condition. The fabricated FMB diode module could detect signals in a wide frequency range from 160 GHz to 1.4 THz with a low noise equivalent power (NEP) of 3 ×10^-12 W/√Hz at 300 GHz in the square-law detection mode. In the mixing detection mode, very low NEPs of 1.6 × 10^-17 W/Hz for homodyne detection with a local oscillator power (P_LO) of 5 ×10^-7 W and 1.1 × 10^-18 W/Hz for heterodyne detection with a P_LO of 6 × 10^-6 W were achieved at 300 GHz. We also developed a linear detector array consisting of 100 FMB diodes for THz-wave imaging and accomplished a near diffraction-limited resolution at 315 GHz.