Han Jung

Smart CMOS Charge Transfer Readout Circuit for Time Delay and Integration Arrays

This paper presents a novel CMOS charge transfer readout circuit for X-ray time delay and integration (TDI) arrays with a depth of 64. The proposed circuit uses a charge transfer readout similar to CCD; thus, the summing of the signal charges can be implemented easily compared with other typical CMOS readout circuits for TDI arrays. The weakness of TDI arrays related to defective pixels can be solved by integrating a dead pixel elimination circuit. In addition, the proposed method can be applied to a TDI arrays with large depths, so a high signal to noise ratio (SNR) can be acquired. The readout chip has been fabricated using a 0.6 mum standard CMOS process for 150times64 CdTe X-ray detector arrays. It was found that the readout circuit can effectively increase the charge storage capacity up to 1.6times109 electrons, and then provide an SNR improved by a factor of approximately 8

Dark current reduction of InGaAs photodiode by low stress diffusion mask

InGaAs detector for SWIR imaging is widely used for remote sensing, medical application, personal identification etc. To reduce the required power for various environmental condition, reducing dark current is crucial. The dark current of InGaAs detector is known to come from defects induced during the growth of wafers and the process to fabricate FPAs. Especially, when high temperature is applied for the diffusion of Zn to form p-type junction on n-type InP/InGaAs substrate, the diffusion barrier of Zn on the substrate experiences large expansion and add stress in the substrate. The induced stress will increase defects and increase dark current. In this work, to reduce the stress of the Zn diffusion barrier, balanced diffusion barrier with multiple layer is applied. By reducing the stress, the dark current density has reduced to below 10 nA/cm2, which is suitable for low power operation.

Current status of cooled IR detectors at i3system

This paper shows the current status of cooled IR detector technologies at i3system, South Korea. Mass production technology of i3system has successfully supplied lots of QVGA cooled IR detectors to camera customers. i3system has also developed small pitch cooled IR detectors with 320×256 and 640×512 formats for several different applications such as thermal sights and 24-hour operation observation units. In 2013, i3system’s cooled IR detector has been launched in STSAT(Science and Technology SATellite)-2C through Naro-1 program which was South Korea’s first successful launch vehicle for satellite. Owing to i3system’s robust, intensive design and test programs, IR detector technologies have been space qualified without any further efforts by the space program. Currently, development programs for SXGA(1280×1024) with small pitch cooled detector are being progressed and its status is addressed.

Performance Comparison of Thermal Imagers with Uncooled and Cooled Detectors For Fire Fighting Application

Thermal Imaging systems are reported to be crucial for fire fighting and beginning to be used by fire fighters. The performance of thermal imaging system is determined by both the radiation of infrared from the target and the attenuation of infrared signal in the optical path by the absorption, scattering, diffraction and reflection. In the scene of fire, water drops with various sizes such as vaporized water, wafer mist from sprinkler, and wafer to suppress the fire reside with various gas generated by burning. To measure the transmission of infrared radiation in the scene of fire, fire simulating system and thermal imagers with cooled detector which detects infrared and uncooled detector fabricated by the MEMS technology which detects infrared. are made. With thermal imagers and Ire simulating system, the change of thermal image with respect to the change of visibility controlled with the burned fas was measured. It was found that the transmission of infrared was not reduced by the burned gas, which could be explained by the long wavelength of infrared ray compared with visible ray. However, the transmission of infrared ray was largely reduced by the combination of burned gas and water mist supplied by sprinkler. This is contrary to the results of calculated transmission through the pure water mist and shows that the transmission of infrared ray is mostly affected by the compounds of water mist and burned gas. In this case, it was found that the uncooled detector which detects infrared ray is better than cooled detector which detects infrared ray for fire fighting.

Development of mid-wave 320x256 infrared focal plane array in Korea

This paper reports the development of mid-wave 320x256 HgCdTe IRFPA with 30μm pixel pitch since 2002 in Korea. All key technologies such as HgCdTe photodiode array fabrication process, the design of silicon readout integrated circuit and hybridization process between HgCdTe photodiode array and ROIC including underfill encapsulation process are studied and realized. The fabricated IRFPA shows good electro-optical performances such as operability over 99%, NETD of ~ 17mK and there is no degradation in the operability during 500 thermal cycles.