Proton induced luminescence in the HgCdTe detectors for the Wide Field Camera 3 instrument has been investigated. A radiation experiment has been conducted to localize the source of the luminescence. Conclusive evidence is shown that the luminescence originates in the CdZnTe substrate and propagates toward HgCdTe photodiodes as ~800 nm radiation. Luminescence is proportional to the proton energy deposited in the substrate. Subsequent testing of detectors with the substrate removed confirmed that substrate removal completely eliminates proton induced luminescence.
The wide variety of optoelectronics applications in NASA flight systems and instruments require that optoelectronic technologies meet the demanding requirements of the space environment throughout mission life. These requirements vary widely from intense radiation near Jupiter to the very cold temperatures on the Martian surface to the effects of solar flares in Earth orbit. Considerable work has been performed under the NEPP Program to meet these assurance needs and minimize the risk of insertion of optoelectronics in NASA systems. In this paper we provide recent examples of this work for a variety of NASA mission applications that employ various optoelectronic devices.
The operability requirements of NASA's James Webb Space Telescope (JWST) impose specific challenges on radiation effects mitigation and analysis. For example, the NIRSpec Instrument has the following requirements: •The percentage of pixels defined as operable for target acquisition shall not be less than 97% (TBR) (goal 99%) of the total number of pixels... An inoperable pixel is: ο A dead pixel: a pixel with no radiometric response o A noisy pixel: a pixel with a total noise greater than 21 e-, per Fowler 8 exposure •The percentage of pixels defined as operable for science observations shall not be less than 92% (TBR) (goal 98%) of the total number of pixels... An inoperable pixel is: ο A dead/low-DQE pixel: a pixel deviating by >30% from the DQE mean value ο A noisy pixel: a pixel with a total noise greater than 12 e- (goal 9e-). With these performance requirements and operation in space, the radiation environment from galactic cosmic rays (GCR), energetic solar particles, and activation of spacecraft materials can contribute significantly to the number of inoperable pixels. The two most important issues to date are radiation-induced transient effects and hot pixels. This paper focuses on the methods used to assess the impact of ionizing radiation induced transients on the HgCdTe SCA selected by JWST. Hot pixel effects in these detectors has been previously presented. Both effects are currently under investigation.
A Hubble Space Telescope Wide Field Camera 3 (WFC3) CCD detector was tested for radiation effects while operating at -83C. The goal of the experiment was to evaluate the introduction and annealing rates of hot pixels and to assess the dynamics of that process. The device was irradiated while cold and warmed to +30°C for a 4 hour soak, then cooled back down to -83°C. Hot pixel populations were tracked during warm up and cool down. The results showed that the hot pixels begin to anneal around -40°C and the anneal process was largely completed before the detector reached +30°C. It was also found that, although a large fraction of the hot pixels dropped below the threshold, they remained warmer than the remaining population.
The proton-induced charge transfer efficiency (CTE) behavior for the Lawrence Berkeley National Laboratory (LBNL) p-channel CCD [being developed for the Supernovae Acceleration Probe (SNAP)] is compared with the Hubble Space Telescope’s (HST) Wide Field Camera 3 (WFC3) n-channel CCDs CTE using 55Fe x-rays, first pixel edge response (FPR), and extended pixel edge response (EPER) techniques. The pre- and post-proton radiation performance parameters of p-channel CCDs designed by LBNL and fabricated at Dalsa Semiconductor, Inc. are compared with n-channel CCDs from E2V, Inc. LBNL p-channel CCDs both with and without notched parallel registers are compared with the E2V CCD43 [a notched, multi-phase pinned (MPP) device] and the E2V CCD44 (an un-notched, non-MPP device), using the same readout timing and measured over the same range of temperatures. The CTE performance of the p-channel CCD is about an order of magnitude better than similar n-channel CCDs for the conditions measured here after a 63 MeV proton fluence of 2.5 x 109 cm-2, which is equivalent to 2.5 years in the HST orbit behind shielding comparable to about 2.5 cm Al. Our measurements are compared with previous CTE measurements at 12 MeV by Bebek et al. The ~ 10 x CTE improvements relative to n-channel CCDs is seen at -83°C, a temperature which is optimized for n-channel CCD performance. Advantages from p-channel CCDs should be greater at other temperatures. Dark current measurements and hot pixel issues are also discussed.
A Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) flight-like IR detector was tested for radiation hardness by exposing it to high energy protons while operating at the nominal flight temperature of 150 K. The detector is a 1.7 μm cutoff HgCdTe detector with a CdZnTe substrate. The device is hybridized to a silicon multiplexer. The detector response was tested for gradually increasing fluence from less than 1x103 to a total of 5x109 63 MeV protons/cm2. Dark current changes were evaluated after each step. An increase in dark current and new hot pixels were observed after large steps of irradiation. The increased dark current was observed to partially anneal at 190K and fully anneal at room temperature. Radiation effects, hot pixel distribution, and results of annealing at different temperatures are presented here.
In November 2003, a Space Environmental Effects Working Group meeting in El Segundo, CA developed technology roadmaps and recommended Government investment strategies for key technologies needed for large space imaging systems. This paper summarizes results from the session on focal plane array (FPA) technology. The FPA session
recommended continued emphasis and additional investments to strengthen the manufacturing infrastructure for production and test of advanced focal planes and readouts, especially those operating at cryogenic temperatures and in radiation environments.
A Hubble Space Telescope Wide Field Camera 3 (WFC3) CCD detector was tested for radiation effects while operating at -83°C. The detector has a format of 2048 x 2048 pixels with a 15 μm square pixel size, a supplemental buried channel, an MPP implant, and is back side illuminated. Detector response was tested for total radiation fluences ranging from 1x103 to 2.5x109 of 63.3 MeV protons/cm2 and for a
range of beam intensities. Radiation damage was investigated and the annealing of damage was tested by warming up to +30°C. The introduction rate of hot pixels and their statistics, hot pixel annealing as a function of temperature and time, and radiation changes to the mean value of dark current were investigated. Results are compared with the experiences of other HST instruments.
As the logical extension of the 20-year mission of the Hubble Space Telescope, NASA plans to launch the James Webb Space Telescope (JWST, formerly NGST) near the end of this decade. As Hubble's scientific and technological successor, equipped with a 6-meter-class deployable mirror, JWST will allow observations of the very early universe
and initial formation of galaxies at levels not achievable today. JWST's unprecedented sensitivity cannot be utilized without a new class of IR focal plane arrays whose performance matches that of the telescope. In particular, JWST focal planes must be able to withstand the ionizing-particle radiation environment expected for its Lagrange-point (L2) orbit and ten-year mission lifetime goal. To help determine their suitability for JWST, NASA is evaluating prototype
megapixel-class readouts and hybrid detector arrays under proton bombardment to simulate the anticipated JWST lifetime radiation dose. This report describes the results of early tests on devices from two manufacturers using photovoltaic (HgCdTe or InSb) candidate near-infrared detector structures. Results to date have shown encouraging
performance, along with some areas of continuing concern.
KEYWORDS: Charge-coupled devices, Sensors, Iron, Calibration, CCD cameras, Cameras, Hubble Space Telescope, Signal to noise ratio, Space telescopes, Interference (communication)
Proton induced charge transfer efficiency (CTE) degradation has been studied in the large format charge-coupled device (CCD) flight-like candidates for Wide Field Camera 3 for the Hubble Space Telescope. These detectors were irradiated with different proton fluences. This
paper focuses on the statistical nature of CTE degradation due to damage on one of the irradiated devices with exceptional initial CTE characteristics. In radiation damaged CCDs, CTE noise can be the dominant noise component. In contrast to other noise sources, CTE noise has a component of fixed pattern noise that can be removed by the appropriate calibration technique. A large set of data was acquired and analysis of it confirms the expectation that CTE damage is a local phenomenon and it varies widely across the CCD surface. Possible mitigation solutions and their practicality are discussed in some detail.
The dual-rate 1773 (DR1773) fiber optic data bus (FODB) experiment is one of twenty four space fight experiments on the Naval Research Laboratory's (NRL) microelectronics and photonics test bed (MPTB). MPTB is an NRL satellite payload that will be composed of modern technology microelectronics and photonic experiments. The Goddard Space Flight Center (GSFC) experiment on MPTB will evaluate the in-flight performance characteristics of the Society of Automotive Engineers (SAE) Aerospace Standard (AS) 1773 FODB in the space radiation environment. AS1773 is a passive star coupled FODB that operates at data rates of Mbps and 20 Mbps. This protocol is commonly referred to as 'dual-rate 1773 (DR1773).' Two different DR1773 fiber optic transceiver designs are tested on the experiment. These devices are the Boeing DR1773 and the SCI DR1773 transceiver. The transceiver devices on the experiment are implemented in a star coupled system and are tested at the higher 20 Mbps data rate. It is estimated that DR1773 at 20 Mbps will meet approximately 80% of NASA's current data rate requirements. DR1773's predecessor, Mil-Std-1773, is currently being flown on several NASA spacecraft. Mil-Std-1773 operates at a single rate of 1 Mbps. Because DR1773 is based on an existing bus protocol, incorporating DR 1773 into the NASA spacecraft program would be both time and cost effective. Success of the DR1773 experiment will provide valuable data on the DR1773 FODB space radiation performance as well as proof of concept for use of the DR1773 FODB for future NASA spacecraft systems.
Kenneth LaBel, Mark Flanegan, George Jackson, Donald Hawkins, Cheryl Dale, Paul Marshall, Donald Johnson, Christina Seidleck, Rodney Bonebright, Jae Kim, Eric Chan, Thomas Bocek, William Bartholet
NASA Goddard Space Flight Center (GSFC) along with the Naval Research Laboratory (NRL) has been at the forefront of the space community in terms of the use of fiber optic data busses and links in the space radiation environment. Previously, we have described the ground radiation test program of the small explorer data system (SEDS) 1773 1 Mbps fiber optic data bus (FODB), as well as its associated in- flight space radiation-induced performance. Further work has also been presented covering higher speed photonic components utilizing III-V materials. Because of the success of the SEDS 1773 FODB coupled with the radiation testing of III-V devices, a second generation FODB capable of both 1 Mbps and 20 Mbps operation is being developed for spaceflight utilization. We present herein preliminary ground test radiation results of hybrid transceiver devices manufactured by Boeing Space Systems that perform the electro-optic and opto-electric translations in support of this medium rate FODB, the AS1773 bus. These devices, designed to be radiation hard (or rad hard), will be flying on NRL's Microelectronics and Photonics Testbed (MPTB) payload as a NASA experiment. This experiment is described in detail elsewhere in this proceedings.
In-situ measurements of proton-induced system level errors are reported for newly designed and fabricated hardware implementing an operational 200 Mbps linear token passing fiber optic data bus. Parametric analysis of key single-particle-event and total-ionizing-dose variables affecting components is used to quantify system response and predict on-orbit performance.
The Microelectronics and Photonics Test Bed (MPTB) is a space experiment which will evaluate the performance of components and sybsystems of important new technologies is advance of their deployment of future spacecraft. Devices aboard MPTB will monitor the environment, and the radiation effects data obtained on components will be compared to ground tests and predictions. We present a description of the proposed high performance fiber optic data bus (FODB) experiment for MPTB which will feature the newly available 200 Mbps Boeing STAR-FODB hardware which is designed for space applications. This bus uses a passive star architecture and implements a Linear Token Passing Bus (LTPB) standard. The existence of extensive ground radiation test results for the STAR-FODB will enable high confidence predicition of its on-orbit performance to be made prior to launch.
As spacecraft begin to unlock the potential of fiber optic systems for spaceflight applications, system level bit error rates (BER) become of great concern to the system designer. Fiber optic data busses running up to 1 Gbps data rates require an uncorrected BER to meet system specifications. With emerging high speed and low power devices such as 3 V CMOS and GaAs ICs being utilized in the system design to interface the electronic subsystems to the fiber optics, the BER contribution of these emerging technology devices in the space Single Event Effect (SEE) arena may outweigh that of the fiber optic components. We present data on several emerging technology devices and the implication of their usage in fiber optic systems in the space SEE environment.
A dual rate 1773 fiber optic transceiver chip for space applications is presented. The transceiver will work with either 1 Mbps, or 20 Mbps Manchester data. The receiver features first bit capture with no preamble for 1 Mbps data, and clock recovery for 20 Mbps data. Single event effects in the photo diode are considered in the receiver design. A transmitter switch is included on the chip for driving an LED. The chip will be fabricated in a radiation hard CMOS process.
We consider space radiation effects in components and subsystems for fiber based satellite data links and busses. These busses are designed for telemetry and command as well as payload applications spanning data rates from Mbps to Gbps. We emphasize measurements of single particle transient effects in optoelectronic components as they impact the bit error ratio. Test data are analyzed to demonstrate the bit error rate dependence on the particle energy and particle flux as well as receiver electrical characteristics. We conclude that the many advantages of fiber based data links and busses will soon be made available for emerging satellite requirements to transmit data reliability at rates from a few Kbps into the Gbps regime.
Current developments in high performance satellite data links rely on fiber optic systems to take advantage of light weight, electromagnetic isolation, low power, and high bandwidth. Indications are that fiber data links operate with little degradation or interference in the earth's trapped radiation belts. To quantify this, we report analyses of experimental investigations in which operating fiber bus components are subjected to proton bombardment at varying proton energy, proton flux, angle of incidence, data rate, and signal levels. Parameterization of bit error rate (BER) effects in terms of these variables offers insights into the physical mechanisms involved and suggests both circuit modification and device selection criteria to maximize link performance. We outline a method to predict BER in orbit and offer this as a basis for evaluating proposed hardening solutions. The method combines predicted trapped particle orbital environmental data, including spacecraft shielding effects, with the measured system response.
The Microelectronics and Photonics Test Bed (MPTB) is a space experiment which evaluates the performance of components and subsystems of important new technologies in advance of their deployment on future spacecraft. Devices aboard MPTB monitor the environment, and the radiation affects data obtained on components will be compared to ground tests and predictions. We present a brief description of the candidate NRL (Naval Research Laboratory) photonics experiments for MPTB.
The Small Explorer Data System (SEDS) is a spaceflight command and data handling system for the small explorer (SMEX) program at Goddard Space Flight Center (GSFC). A key component in this system is the SEDS MIL-STD-1773 Fiber Optic Multiplexed Data Bus. The 1773 bus provides a means of passing telemetry and commands between spacecraft subsystems. This bus is currently being considered for additional spaceflight programs inside and outside of the NASA realm. The SEDS 1773 bus uses integrated optoelectronics as part of its electrical subsystem (or user) to optical interface. Generic proton and heavy ion test results have been previously reported. Herein is presented proton test results for continuing this investigation under actual subsystem interface conditions (MIL-STD-1773) as well as for generic devices using the proton test facilities at University of California, Davis (UCD). This testing was undertaken as a joint effort between NASA/GSFC and the Naval Research Laboratories (NRL).
We review radiation effects in components and subsystems for fiber based satellite data bus architectures. These busses are designed for telemetry and command as well as payload applications spanning data rates from Mbps to Gbps. Issues include total ionizing dose to fibers resulting in increased attenuation, total dose and displacement damage in optoelectronic sources and detectors, and single particle transient effects in optoelectronic components. In each case we review component selection criteria and develop quantitative treatments based on experimental data to demonstrate how survivable data busses can be implemented even in severe orbits. We conclude that the many advantages of fiber based data links and busses will soon be made available for emerging satellite requirements to transmit data reliably at rates from a few Kbps into the Gbps regime.
As spacecraft require lighter weight and higher speed communication systems, technologies such as fiber optics have come to the forefront. The space radiation environment, however, can be quite harsh in its effects on a fiber optic system. This paper presents the methodology behind testing integrated optoelectronic receivers and transmitters for single event upsets (SEUs). Two main causes of single event effects in the space environment are discussed, namely protons (trapped and solar flare) and galactic cosmic rays, as well as ground test facilities used to simulate the space environment. The prime emphasis presented herein is on the actual test requirements and system schemes needed for devices such as integrated optoelectronics. The definition of an SEU is unique to each fiber optic system application: a setup that is capable of detecting small signal 'glitches' may not be realistic when the interface circuitry utilizes an overlying system protocol or sampling scheme. Additionally, the expected system utilization rates may also affect the SEU rates. Actual test data and applications are discussed.
We report energy-dependent proton and Co-60 test results and analysis assessing performance of In0.53Ga0.47As photodetectors and In0.71Ga0.29As0.61P0.39 laser diodes for satellite applications. Calculations of the nonionizing energy loss (NIEL) for protons in InGaAs allow damage assessment using a general technique for evaluating displacement damage in orbit. Device performance is predicted for several shield thicknesses and orbital conditions. We also discuss effects in optoelectronic devices due to total dose and ionization transients.
The particle environment within a satellite includes primary and secondary protons and secondary neutrons produced in spacecraft materials which we evaluate using the transport code BRYNTRN. The damaging effects of this mixed particle environment is evaluated for the example of solid state imaging arrays by introducing the concept of displacement damage dose. Having the same relationship as electronic stopping power (LET) and radiation absorbed dose (rad) the nonionizing energy loss rate NIEL) of protons and neutrons are combined in terms of nonionizing radiation absorbed dose (nirad). This quantity is evaluated as a function of Ta and Al shield thickness for both trapped and flare proton environments. Al is shown to be a superior shield material per unit mass partially due to the damaging effects of neutrons which are produced in greater abundance in Ta. This method for combining the damaging effects from all particles using displacement damage dose enables informed shielding decisions and improved prediction of device performance in space. 1.
Particle-induced displacement damage degrades performance parameters in state-of-the-art solid state imagers due to charge transfer inefficiency, increased dark current, and dark current spikes. This paper reviews some recent radiation damage measurements and discusses imager degradation in the context of a general understanding of how displacement damage alters semiconductor properties. An approach to predict the response of a sensor to a given space environment and shielding configuration is presented and the authors briefly discuss other displacement damage concerns such as secondary neutron production in shielding. Using an example based on limited experimental input, the authors demonstrate how higher (10 MeV) energy protons are responsible for over 90 of the damage in heavily shielded imager applications.
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