Yiming Liao

Far-infrared(FIR) technology, spanning the infrared (IR) to terahertz (THz) range, has been limited by the lack of high-sensitivity detectors. Here, a complementary metal–oxide–semiconductor (CMOS) microbolometers with Ti/Si₃N₄/SiO₂/Al metamaterial absorbers (MAs) is designed for the detection range of 10-50 μm. The inverse design of the MAs is applied using binary coding and staged genetic algorithm (SGA) to enhance efficiency and flexibility for ultra-broadband absorptivity. The optimal MAs structure achieves an average absorptivity of 82% across the 10-50 μm range and shows excellent tolerance to polarization and incidence angle variations. Thermal simulations reveal that microbolometer with MAs achieves a 162.1% increase in maximum temperature rise. This research provides a performance-optimized and highly integrable solution for extending the detection range of CMOS-based FIR detectors, addressing key challenges in ultra-wideband photodetection across IR to THz wavelengths.

Multi-spectral imaging enhances the information diversity of the object with complex, expensive, and low integrated components. Here, we demonstrated an antenna-coupled microbolometric detector in complementary metal-oxide-semiconductor (CMOS) technology, utilizing SiO2 absorption and L-shaped fractal antenna to achieve multi-band detection from infrared (IR) to terahertz (THz). Experimental results demonstrate that the detector can achieve high sensitivity detection in both THz and IR bands, with the maximum detectivity of 5 (10⁸ cm·Hz^1/2/W @305 GHz and 7 (10⁸ cm·Hz^1/2/W @8.55 µm, respectively. The presented multi-spectral detector is easily implementable in integrated circuit process, conducive to high-density, low-cost, and high-performance array imaging.

The practical applications of microbolometers in CMOS technology face challenges since the thermometer layers in microbolometers are typically of low IR absorption coefficients. In this paper, we demonstrate the integration of IR metal-insulator-metal (MIM) plasmonic absorber on the CMOS resistive-type microbolometers to maximize the optical detectivity. The MIM absorbers utilize Al metals and SiO₂ dielectric films in the standard CMOS process and the configuration is numerically simulated and analyzed to assess the effectiveness of high IR absorption through propagating surface plasmon (PSP) resonance and localized surface plasmon (LSP) resonance. Experimental results show that the microbolometer integrated with the MIM plasmonic absorber has a 64% improvement in detectivity (D*) compared to the one without MIM absorber in the 7-13 µm wavelength range. The detector yields a maximum D* of 2.46 × 10⁹cm Hz^1/2/W at 9.5 µm optimally under a working current of 30 μA. This performance-enhanced microbolometer provides a pathway for achieving ultra-sensitive imaging using a simple, cost-effective manufacturing process.

The growing need for the multiband photodetection of a single scene has promoted the development of both multispectral coupling and broadband detection technologies. Photodetectors operating across the infrared (IR) to terahertz (THz) regions have many applications such as in optical communications, sensing imaging, material identification, and biomedical detection. In this review, we present a comprehensive overview of the latest advances in broadband photodetectors operating in the infrared to terahertz range, highlighting their classification, operating principles, and performance characteristics. We discuss the challenges faced in achieving broadband detection and summarize various strategies employed to extend the spectral response of photodetectors. Lastly, we conclude by outlining future research directions in the field of broadband photodetection, including the utilization of novel materials, artificial microstructure, and integration schemes to overcome current limitations. These innovative methodologies have the potential to achieve high-performance, ultra-broadband photodetectors.

In this paper, a novel approach that combines technology computer-aided design (TCAD) simulation and machine learning (ML) techniques is demonstrated to assist the analysis of the performance degradation of GaN HEMTs under hot-electron stress. TCAD is used to simulate the statistical effect of hot-electron-induced, electrically active defects on device performance, while the artificial neural network (ANN) algorithm is tested for reproducing the simulation results. The results show that the ML-TCAD approach can not only rapidly obtain the performance degradation of GaN HEMTs, but can accurately predict the progressive failure under the work conditions with a mean squared error (MSE) of 0.2, informing the possibility of quantitative failure data analysis and rapid defect extraction via the ML-TCAD approach.

Although surface plasmon resonance (SPR) antennas have been integrated into CMOS THz detectors as an alternative to the traditional radio-wave antenna, spatial crosstalk of SPR antenna in detector arrays remains an issue and there is little study in this field. In this paper, a CMOS THz detector array at 0.65 THz with on-chip SPR antennas is designed in standard CMOS technology and the pixel crosstalk related to the SPR antenna parameters are investigated. Simulation results show that the adjacent SPR antenna spacing significantly affect the antenna crosstalk due to the surface wave propagation. To suppress the pixel crosstalk, the adjacent SPR antenna spacing is designed as 1.65 times larger than half of the antenna size. Under the condition, the S12 parameter between the adjacent antennas is reduced to -15 dB. High antenna isolation can be further available by the increase of the isolation layer thickness of the pixel up to 1 m. Based on the simulation results, a 116 THz detector array at 0.65THz was fabricated. The experimental results show that the pixels in the array achieve uniform NEP, with an average value of about 32.6 pW/Hz0.5 and a standard deviation coefficient of about 9.6 %. The results can be further optimized to meet various crosstalk requirements for CMOS THz detectors.

In this paper, we designed a CMOS terahertz (THz) detector array based on surface plasmon resonance (SPR) antennas using a 55nm CMOS process technology. The 8*8 pixel array consists of SPR antennas, NMOS THz detectors, on-chip 45.96dB amplifier, and AD converter. We mainly studied the level of crosstalk between pixels at different antenna spacing. Besides, we designed artificial magnetic conductor (AMC) to reduce the level of the crosstalk. Simulation results show that the electrical crosstalk drops significantly by optimizing the antenna spacing and employing AMC structure.

The saturation current variability σ(δI _dsat) and lifetime variability in hot carrier injection (HCI) have been investigated for deeply scaled nMOSFETs. It is found that both of them are getting worse with scaling down. The statistical analysis of the large data sets from various CMOS sizes shows that σ(δI _dsat) is dominated by the total number of Poisson-distributed defects generated by HCI stress and the length (L) and width (W) of these devices. We attempt to use a single parameter to accurately describe HCI variability in deeply scaled nMOSFETs.