Fig. 1. (a) The schematic diagram of the FP resonance principle of the device. The microcavity enhancement effect can be directly obtained by measuring the detection performances of the device with and without the bottom Au mirror, respectively. (b) The schematic diagram of IV curve with THz irradiation. (c) The schematic diagram of the two-temperature heat transfer model, the hot electron temperature (red line) and Seebeck coefficient (blue line) distributions along the graphene channel.

Fig. 2. (a) The reflection spectra of a silicon slab with different thicknesses and an Au mirror mounted at the bottom of the slab. (b) The schematic diagram of the resonant frequency of the dipole antenna with different arm lengths. (c) The surface-averaged electric field enhancements in the feed slot region as functions of frequency for the cases of infinite silicon substrate, 243-μm thick silicon slab, and 243-μm thick silicon slab with an Au mirror mounted at the bottom, respectively. The single arm length of the antenna is 500 μm. (d) The surface electric field distribution (top) and vertical electric field distribution (bottom) in the feed slot region at the resonant frequency of 95 GHz of the microcavity–antenna structure.

Fig. 3. Optical microscope images of the asymmetric antenna coupled THz PTE detectors with a magnification of 100 (a) and the detailed structure near the feed slot region with a magnification of 500 (b). (c) The AFM image of the graphene channel. Inset is the AFM line profile. (d) IV characteristic curve of the device. Inset is the scanning electron microscope (SEM) image of the graphene channel with a magnification of 3500.

Fig. 4. Peak response of the microcavity–antenna integrated graphene detector at 99 GHz. (a) Pulse response current of the graphene PTE detector. (b) The rise and fall response times of the device. (c) The IV curves with and without THz irradiation. (d) Polarization-dependent response current of the device.

Fig. 5. (a) The photocurrent with respect to the distance d at frequency 99 GHz. Insert is the schematic diagram of the effective FP cavity composed of the emission port of the coherent THz source and the Au mirror at the bottom of device substrate. (b) The origin (blue) and fixed (red) photocurrent spectra. The voltage responsivity spectra of the device with (red) and without (blue) Au mirror mounted at the bottom of the substrate (c) and the corresponding noise equivalent power (NEP) (d).

Fig. 6. (a) Structure diagram of the one-dimensional two-temperature heat transfer model. (b) Temperature distribution of the graphene electron and lattice between the source and drain electrodes. (c) The temperature difference between the graphene and electrode changes linearly with the incident power. (d) The variation of the maximum temperature difference between the graphene and electrode with heat relaxation time and electron heat capacity.

Fig. 7. (a) Schematic diagram of the measurement system. (b) THz transmission spectrum of silicon wafers.

Fig. 8. Schematic diagram of device fabrication.

Fig. 9. Schematic diagram of the device measurement system.

Fig. 10. (a) The response current at different modulation frequencies. (b) The response current at different output powers under 14.8 GHz illumination.

Fig. 11. The voltage noise density spectrum of the device measured at room temperature and in zero bias condition. The black dashed line is the Johnson–Nyquist white noise.

Fig. 12. Photocurrent with respect to the distance d at 99 GHz when the Au mirror is removed.