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Terahertz (THz) detecting technology has attracted many attentions. In this work, a novel THz detector based on a metal gratings/Si-based blocked-impurity-band (BIB) hybrid structure was designed and theoretically calculated. The highly integrated hybrid structure was found useful for modulating the response wavelength and improving the responsivity of Si-based BIB detector. The enhanced THz absorption of the hybrid device structure of metal gratings and Si-based BIB absorption layer was carefully investigated by finite difference time domain. The peak wavelength can be moved from 26.9 to 36.53 μm when metal gratings (period: 32 μm) were added on the Si-based BIB. The peak absorptivity of the hybrid detector was increased by 87.3 % with the metal gratings, compared with that of conventional Si-based BIB detector. Our results indicate that a highly integrated hybrid device structure can replace the divided band filters, and realize selective resonant enhanced absorption and tunable THz spectral response.

Terahertz (THz) photodetector has attracted great attention from worldwide scientists for its applications in security check, biomedical treatment, and astronomical observation. In the performance evaluation of the THz photodetector, the noise level is one of the critical parameters. The Gallium Arsenide (GaAs) blocked-impurity-band (BIB) detector, which is fabricated from intrinsic GaAs-based photoconductive detectors, reveals an attractive advantage of low dark current value and high signal to noise ratio (SNR). In this work, the epitaxial GaAs BIB detector was fabricated and its noise behavior under various bias was investigated at the temperature of 3.5 K. The measured noise consists of flicker noise (1/f noise), shot noise, thermal noise and measurement noise. The effect of bias and operation temperature (TOpe) on the noise characteristics of a GaAs-based BIB detector has been studied by numerical simulation for suppressing device noise. According to the simulation, the total noise gradually increases with TOpe, and dominated by the shot noise. Our work may provide useful theoretical support to solve the critical epitaxial growth bottleneck of GaAs BIB detector and improve its performance for the applications of astronomical observation, security check, etc.

The structural model and fabrication process of the Si-based blocked-impurity-band (BIB) detector were proposed. The numerical simulation of phosphorus ion implantation and rapid thermal annealing was investigated. Various implantation conditions were analyzed to meet the requirements of good electrical contact. Moreover, the carrier activation effect of phosphorus ion implantation and rapid thermal annealing was demonstrated by Hall test. Then the relationship between blackbody responsivity and annealing temperature was analyzed. According to the measurement results, the blackbody responsivity and response wavelength range of Si-based BIB detector we fabricated can reach 2.2A/W and 5–45 μm, respectively. Our work shows that the good electrical contact can improve the blackbody responsivity. It provides an effective method to fabricate Si-based BIB detector with good performances.

Terahertz (THz) photodetectors have attracted great attention from scientists worldwide for their application in security checking, biomedical treatment and astronomical observation of remote stars and distant galaxies. As a typical THz detector, extrinsic GaAs based photoconductive detector is facing critical technical bottlenecks in the epitaxial growth of sufficiently thick and high-quality GaAs absorption layer. In this work, a novel THz photoconductive detector based on metamaterial/GaAs/electrode layer hybrid structure was designed and simulated. By setting the periodic split ring resonator (SRR) structure as 88 μm pitch with 8 μm width, the absorption peaks exist at the wavelength of about 142 and 367 μm, which originate from the resonant cavity and the SRR dipole resonance effect, and the novel device shows a significant enhancement compared with the conventional GaAs photoconductive detector. Thus, the necessary thickness of GaAs absorption-layer is largely reduced, and the resonant absorption peak can be modulated by changing the thickness of absorption layer. This work provides a novel device structure which can solve the critical epitaxial growth bottleneck of GaAs photoconductive detector and used for the astronomical observation, security check, etc.