This article mainly studies the current voltage (IV) characteristics of Quantum Well Infrared Photo-detectors, especially the influence of temperature on their performance, as well as the characteristics related to photocurrent and dark current. We measured the IV curves at different temperatures and conducted comparative studies to reveal the differences in the behavior of quantum well devices under photoexcitation and non photoexcitation conditions, in order to gain a deeper understanding of their performance characteristics. Finally, we investigated the response of quantum well devices to different blackbody temperatures and fitted the dark current using the IV curve, which was compared with the actual measured dark current. The results show that the fitted dark current is slightly larger than the actual measured dark current. Through these studies, we can comprehensively understand the IV characteristics of quantum well devices under different temperature and lighting conditions, providing strong support for their optimization and control in various applications. These research results are of great significance for the design and engineering applications of QWIP.
Quantum well infrared photodetectors (QWIPs) have natural advantages, such as high material maturity and good uniformity. But its low quantum efficiency is often criticized as a drawback. The quantum well optical coupling structure is one of the key factors affecting the quantum efficiency of quantum well detectors. This article mainly focuses on the impact of the optical coupling structure of quantum well detectors on detector wavelength, coupling efficiency, and other aspects. We have established an optical coupling structure model for quantum well detectors, mainly consisting of three different angles of structure structures: 45 degrees, 62 degrees, and 90 degrees periodic two-dimensional diffraction gratings. The 3D-FDTD simulation method was used to simulate the optical coupling structure of quantum well detectors, and the performance indicators of the three structures, such as response wavelength and coupling efficiency, were compared. At the same time, simulations were conducted on different angles of periodic two-dimensional diffraction gratings. It can be seen that as the grating angle increases, the response spectrum width widens, but the amplitude of the response decreases.
To meet the desire of radiation-hardened Electro-Static Discharge (ESD), a series of ESD protection devices and structures were proposed for ultraviolet (UV) AlGaN focal plane arrays (FPAs) readout circuit in this paper. The whole-chip ESD protection structures for I/O pads and power clamp (PC) pads fabricated in Global Foundries 0.35μm 2P4M mixed signal process are investigated. The structure-level and layout-level radiation hardened technologies are used to solve the problem of ESD current discharge efficiency and radiation hardened. Experimental results were obtained by transmission line pulse (TLP) testing system before and after the radiation hardening, it shows that the proposed ESD protection structures can reach the Human Body Model(HBM) ESD level to more than 4kV, while the total dose of ionizing radiation(TID) was 50krad (Si). Moreover, the whole chip ESD protection network are separated into logic ESD protection modules and analog ESD protection modules respectively to decrease crosstalk effect, and multi power clamp ESD protection devices are placed to improve the ESD current discharge efficiency.
Corona discharges occur in high voltage electrical equipment in case of defects and damage, while ultraviolet(UV) light generated during discharge. High resolution imaging in the solar-blind UV bands has a lot of applications in corona discharge detection. A ultraviolet imager based on 320×256 solar-blind AlGaN focal plane arrays (FPA) was designed that work even in the sunlight, because the Cut-off wavelength of the AlGaN FPA is 280nm. The UV image signal processing system based on FPGA is composed of various function modules include the voltage bias, sequence drive, A/D data acquisition, non-uniformity correction, video transformation. Due to FPGA-based data acquisition and realtime image processing technology, the UV imager can operate at a rate up to 100 frame/s. The results show that the simulation high voltage ultraviolet image can be obtained by the UV imager. The image non-uniformity correction performed is one-points correction method to realize background subtraction. And the images show good uniformity and contrast. The UV image of the alcohol burner flame can be detected by the Ultraviolet Imager. Imaging quality was discussed which can be determined by signal-to-noise ratio (SNR), the integration time, the optics f/number and so on. The best imaging conditions were analyzed and the imaging system was designed and setup. The conclusion is proved that the ultraviolet imager based on solar-blind AlGaN FPA provides a new method for corona discharge detection of high voltage power transmission and distribution system.
A Readout Integrated Circuit (ROIC) for GaN ultraviolet (UV) focal plane array (FPA) working in “solar-blind” band is studied in this paper. It has a format of 320×256 and a pixel pitch of 30μm. This circuit can operate both in integrating-while-reading (IWR) and integrating-then-reading (ITR) mode with the frame rate higher than 100fps. It is common that trade-offs always exist between chip power consumption and performances in integrated circuits design. In order to get high injection efficiency with small area and low power, A novel low-power capacitive-feedback trans-impedance amplifier (CTIA) with snapshot mode is designed for the proposed circuit. The smallest operational current of CTIA is only 10nA for 5V power supply. The total power consumption of ROIC is reduced significantly to 45mW with the ultra-low-power pixel. By adopting the 0.35μm 2P4M mixed signal process, the high-performance CTIA architecture can make two gain selections which charge capacities are 3.4Me - and 0.16Me - per pixel with 2.5 V output range. According to the experimental results, this circuit works well under 5V power supply and achieves 8MHz pixel-data-transmission rate.
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