Responsivity enhancement of a strained silicon field-effect transistor detector at 0.3 THz using the terajet effect

Abstract

We report on the enhancement of responsivity by more than one order of magnitude of a silicon-based sub-terahertz detector when a mesoscopic dielectric particle was used to localize incident radiation to a sub-wavelength volume and focus it directly onto the detector. A strained-silicon modulation field-effect transistor was used as a direct detector on an incident terahertz beam at 0.3 THz. A systematic study in which Teflon cubes were placed in front of the detector to focus the terahertz beam was performed. In this study, cubes with different sizes were investigated, and an enhancement of the responsivity up to 11 dB was observed for a cube with an edge length of 3.45 mm (or 3.45 λ ). Electromagnetic simulation results were in good agreement with the experimental ones and demonstrated that the size of the mesoscopic particle plays an important role in focalizing the electric field within an area below the diffraction limit. This approach provides an efficient, uncostly, and easy to implement method to substantially improve the responsivity and noise equivalent power of sub-terahertz detectors.

Optical Phenomena in Mesoscale Dielectric Particles

“…The interesting terajet applications include the gain in sensitivity of terahertz detectors by localized downward radiation in a subwavelength volume [60][61][62], gain in sensitivity of open microwave resonators [63], the use of terajet generating mesoscale particles as a dielectric small-sized antenna in promising terahertz communication systems, including 5G-6G [64,65], and others.…”

Large Area Flexible Thin Layer Terahertz Detector

“…Main performance and detection bandwidth of terahertz detectors based on different materials. [1][2][3][4][5][6][7][8][9][10][11] is on the nanoscale, which can limit its application. The equivalent noise power is another important metric for detectors, and further improvement of the optical responsivity and reduction of the total noise level can reduce the equivalent noise power, which can be seen in Figure 1.…”

Improvement of an InfraRed Pyroelectric Detector Performances in THz Range Using the Terajet Effect

“…Usually, the responsivity of PDs in the THz range is improved by: (i) a traditional gate structure with the grating-gate structure [28]; (ii) implementation of a silicon lens [29], diffractive grating [30], or wavelength-scaled dielectric cube [31,32]; and (iii) internal integration of an antenna structure [33,34]. All these methods, except for [31,32], require a change in the internal structure of the THz detector and its design and are intended for special operation in the THz range.…”

“…Usually, the responsivity of PDs in the THz range is improved by: (i) a traditional gate structure with the grating-gate structure [28]; (ii) implementation of a silicon lens [29], diffractive grating [30], or wavelength-scaled dielectric cube [31,32]; and (iii) internal integration of an antenna structure [33,34]. All these methods, except for [31,32], require a change in the internal structure of the THz detector and its design and are intended for special operation in the THz range. In our work, we consider the use of an IR detector for operation in a non-standard THz range not intended by the detector manufacturer and show for the first time that without changing its internal design, it is possible to increase its sensitivity not in the IR but in the THz range.…”

“…Like photonic jets in optics, it localizes intense electromagnetic beams formed near the shadow surface of a dielectric particle with a size greater or even equal to the illumination wavelength and propagating into the environment. It has recently been demonstrated that placing a dielectric cube in front of a sensitive area of strained silicon field effect transistor [32,46] and point contact detector [31] allows the sensitivity of THz detectors to be increased due to the localization of the incident radiation with the slight decreasing of NEP value. Here, we demonstrate that this method allows one to increase the sensitivity of IR commercial detectors in the THz range with room temperature operation.…”