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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.

The electron transport in AlGaN/GaN HEMTs was investigated using the strain model by Sentaurus TCAD simulations. The impact of strain variations on electron transport properties was studied. The adjustment of strain is achieved by changing strained lattice constant (a) and the strain relaxation (R) in AlGaN layer based on strain model, and then the relationship between piezoelectric polarization and strain values is discussed. The results show that an external tensile strain in AlGaN layer has a strong influence on the distribution and concentration of 2DEG located close to the AlGaN/GaN interface. Meanwhile the threshold voltage and saturated drain current are proportional to the strain values, and the breakdown voltage is improved due to the adjustment of strain. Furthermore, the change of electron transport was also investigated by decreasing the local strain near the gate edge in AlGaN layer. It can be founded that the surface electric field becomes more uniform and the breakdown voltage is enhanced. The results based on the relation between strain and electron transport are beneficial to regulate the electrical properties in AlGaN/GaN HEMTs.

A novel Terahertz (THz) detector based on metallic gratings/GaAs-based Blocked Impurity Band (BIB) hybrid structure was designed and simulated in this work. By setting the periodic metallic gratings as 100μm with 50μm width, the absorption peak of the hybrid structure detector exists at the wavelength of 249 μm, which is 4.84 times larger than the conventional BIB detector. Also, the resonate absorption peak can be modulated by changing the period of metallic gratings. Our design and simulation result provide a new scheme to fabricate the high-performance THz detector for the practical applications such as security check, biomedical treatment, and astronomical obseveration etc.

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.