Advanced charge injection devices for space instruments

Charge Injection Devices (CIDs) have historically played a niche role in visible imager technologies, mainly for applications requiring high radiation tolerance. They have not exhibited the radiometric performance of competing visible- imaging technologies such as CCDs, and so have not been widely applied to space instrument systems. Recent advances in CIDs have demonstrated much higher radiometric performance as well as lower noise operation, without compromising the radiation tolerance of the devices, making the devices suitable for a wide range of space instruments. We present radiometric, noise, and radiation response data for several of the newest CID designs that are candidate technologies for visible space telescope systems. Charge injection devices (CIDs) were developed at approximately the same time as the nearly -ubiquitous charge- coupled device (CCD), but have not received the same acceptance in the scientific imaging community. This is primarily due to the higher read noise inherent in the design in which the output amplifier must "see" the capacitance of the entire device, whereas the CCD has a very low read noise due to a small readout capacitor. However, CID's have also historically demonstrated a vast superiority to the CCD in radiation tolerance, with some designs demonstrating capabilities in the mega-rad range. CCDs are well known to be susceptible to both ionizing and non-ionizing radiation damage, which can limit their performance in a space-based application by dramatically decreasing the charge transfer efficiency whereby charge is moved from one pixel to the next. We discuss a new development in CID technology which focuses on devices that can be used in a stellar reference unit (star tracker). This development effort was initiated by the Jet Propulsion Laboratory, under the Europa Orbiter program, who which demonstrated a need for a highly radiation- tolerant imager that could withstand the high-energy electron environment around Jupiter. The high-energy electron environment produces lifetime damage effects (total ionizing dose and silicon displacement damage effects) as well transient noise generated caused by the high-energy electrons impinging on the pixel storage units and generating spurious signal. The device is also designed needed to meet the radiometric requirements for use in a moderately accurate star tracker. Two devices were developed as a result of this program: the CID816, which features a preamplifier-p er-row design and the CID817, which is a preamplifier-per-pixel design. In addition, a third device is under development (delivered wafers) which is a preamplifier-per-pixel design that is thinned and backside illuminated. The thinning is done to reduce the per-charged-particle noise on the detector by reducing the volume of active material that charged particles can interact with, and Backside thinning illumination is used to increase the fill factor and effective device responsivity.