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Several commonly used space radiation particle transport tools, MCNP, Geant4, FASTRAD, and NOVICE are compared to check the consistency of total ionizing dose (TID) estimates for hardware in a harsh-electron Jovian mission environment. Simple geometries with aluminum, tantalum, and a combination of both materials were used to represent typical and high-density shields. The forward Monte Carlo (FMC) analyses from MCNP and Geant4 were in good agreement within run uncertainty. Compared to FMC results, the reverse Monte Carlo (RMC) analysis results from NOVICE and FASTRAD differed by ±20% ~ ±50%, depending on the simple geometry material. The doses from FASTRAD’s ray-tracing methods differed from NOVICE RMC doses by +60%/−10%. TID analyses of complex as-designed geometries from selected flight instruments and electronics boxes were also compared using the NOVICE and FASTRAD tools. The TID results from these complex geometries with aluminum equivalent thickness ranging from 0.1 to 3000 mil (3 in) differed by as much as +200%/−50% between FASTRAD (ray-tracing and RMC) and NOVICE analyses. We conclude that while MCNP and Geant4 FMC analysis results have extensive experimental validation and therefore provide the most accurate TID estimates, RMC analyses are faster to implement and suitable as conservative tools for missions with a sufficient mass margin. We also conclude that ray-tracing analyses can be suitable during the development phase of shield design optimization for its fast runtime capability.

Multijunction solar cells are fabricated using organometallic vapor phase epitaxy (OMVPE) to deposit subcells of GaInP and GaInAs on 150 mm diameter Ge substrates. We review the general challenges of achieving solar cell epitaxial growth on 150 mm dia. Ge and discuss basic GaInP material characterization. Metamorphic GaInP/GaInAs/Ge C4MJ epitaxial layers are characterized by in-situ curvature measurements during growth. A 98.5% relaxation is measured by high resolution X-ray diffraction reciprocal space mapping, and a threading dislocation density of 1.3×10 5 cm −2 is measured by cathodoluminescence in active regions of the device. Test batches of 20 kWp of cells, 1.0 cm 2 in aperture area, are grown and fabricated on 100 mm and 150 mm dia. Ge wafers and average 40.2% and 40.1% efficiency, respectively, under 50 W/cm 2 AM1.D illuminated current–voltage (LIV) testing. Finally, we demonstrate very large area, >72 cm 2 , triple junction XTJ space devices, averaging 29.3% efficiency for 73 such devices under space LIV testing (0.1353 mW/cm 2 , 28 °C, AM0).

We investigate the effects of both X-ray and proton irradiation on a novel 200 GHz/90 GHz (npn/pnp) complementary SiGe:C HBT technology. The DC forward mode total dose tolerance of the pnp HBTs is shown to exceed that of the npn HBTs by a significant margin after being subjected to both 63-MeV proton and 10-keV X-ray sources, while the AC characteristics of both devices exhibit no degradation up to X-ray doses as high as 1.8 Mrad(SiO2). Pre- and post-irradiation results from a current feedback operational amplifier implemented in this technology and irradiated up to a dose of 1.8 Mrad(SiO2) are presented, showing no degradation in performance metrics under two low current density bias configurations.

We have performed an experimental study of the effects of ionizing radiation and bias-temperature stress on Si MOS devices with HfSiON gate dielectrics. We compare the responses of homogeneous high-SiN films and low-SiN films that contain crystalline HfO. We observe that the low-SiN films are more sensitive to ionizing radiation than the high-SiN films. In particular, the low-SiN film that includes crystalline HfO is especially vulnerable to electron trapping due to substrate injection under positive irradiation bias. Both film types exhibit reduced radiation-induced charge trapping relative to previous Hf silicates. The high-SiN film exhibits less radiation-induced net oxide-trap charge density than earlier Hf silicate films processed without nitride. We also find that these devices are relatively robust against bias-temperature stress instabilities. Consistent with the radiation response, the low-SiN devices also display elevated levels of charge trapping relative to the high-SiN devices during bias-temperature stress.

The radiation tolerance of strained Si/SiGe n-MODFETs is investigated, using 10 keV X-rays, 63 MeV high energy protons, and 4 MeV low energy protons. The effects of radiation exposure on two major device design parameters (LSD and LG) in T-gate Si/SiGe n-MODFETs devices are examined. A strong dependence on source-drain spacing is observed for both the DC and RF characteristics. A drift-diffusion TCAD framework is used for 2-D device simulations. We believe that the low energy protons damage the SiGe/strained-Si/SiGe lattice, leading to partial strain relaxation. The conduction band-offset (CBO) of the strained SiGe/Si heterojunction is lowered leading to higher gate current leakage. The presence of radiation-induced bulk traps in the unrelaxed SiGe layers on the device behavior is also investigated.

The impact of 63.3 MeV proton and 10 keV X-ray irradiation on the DC and AC performance of complementary SiGe HBTs on thick-film SOI is investigated. Proton and X-ray induced changes in the forward and inverse Gummel characteristics, the output characteristics, and avalanche multiplication are reported for both npn and pnp SiGe HBTs, at both room temperature (300 K) and at cryogenic temperatures (down to 30 K). Comparison of room temperature and cryogenic data suggests interface trap formation at two distinct physical locations in the transistors. Experimental data and calibrated TCAD simulations are used to compare the radiation response of both thick-film SOI devices and thin-film SOI SiGe HBTs.

A comprehensive investigation of the performance dependencies of irradiated SiGe precision voltage reference circuits on (1) total ionizing dose (TID), (2) circuit topology, and (3) radiation source is presented. Two different bandgap voltage references were designed using a first-generation (50-GHz) SiGe BiCMOS technology platform, and subsequently exposed to X-rays at doses of 1080 krad(SiO2) and 5400 krad(SiO2). The degradation in circuit performance following X-ray irradiation depends on both the TID level and the chosen circuit topology. Measurement results show that large TID levels can significantly shift the magnitude of the output voltage. Explanations for the observed shifts are provided by utilizing detailed analyses of the two circuit topologies and considering device-to-circuit interactions. The primary factor responsible for the difference in the circuit response before and after irradiation can be attributed to the excess base leakage current in the SiGe HBT. To investigate the impact of radiation source, the circuit topology showing the worst-case degradation from the X-ray experiment was independently exposed to 63-MeV protons at the same effective TID level. A clear source dependence in the circuit response was observed, and possible origins of this behavior are identified.

We present an investigation of the observed variations in the total dose tolerance of the emitter-base spacer and shallow trench isolation oxides in a commercial 200 GHz SiGe HBT technology. Proton, gamma, and X-ray irradiations at varying dose rates are found to produce drastically different degradation signatures at the various oxide interfaces. Extraction and analysis of the radiation-induced excess base current, as well as low-frequency noise, are used to probe the underlying physical mechanisms. Two-dimensional calibrated device simulations are employed to correlate the observed results to the spatial distributions of carrier recombination in forward- and inverse-mode operation for both pre- and post-irradiation levels. Possible explanations of our observations are offered and the implications for hardness assurance testing are discussed

The off-state drain current leakage characteristics of 130 nm CMOS technology are investigated using x-ray irradiation and operating temperature as variables. Radiation-induced interface traps in the gate oxide to gate-drain overlap region strongly enhance the off-state leakage as a function of gate bias. Due to the thin gate oxide in these 130 nm devices, we find that drain-edge direct tunneling is more plausible than conventional gate-induced-drain-leakage in explaining the observed increase in drain leakage. Radiation-induced traps in the shallow trench isolation oxide create parasitic channels in the p-well and produce another source of off-state drain leakage with increasing total dose. The drain current increase from both the gate overlap region and the shallow trench edge are enhanced with increasing total dose and suppressed by cooling

We compare, for the first time, the effects of 63 MeV protons on 1st generation and 3rd generation SiGe HBTs irradiated at both liquid nitrogen temperature (77 K) and at room temperature (300 K). The 1st generation SiGe HBTs irradiated at 77 K show less degradation than when irradiated at 300 K. Conversely, the 3rd generation SiGe HBTs exhibits an opposite trend, and the devices irradiated at 77 K show enhanced degradation compared to those irradiated at 300 K. The emitter-base spacer regions for these two SiGe technologies are fundamentally different in construction, and apparently are responsible for the observed differences in temperature-dependent radiation response. At practical circuit biases, both SiGe technology generations show only minimal degradation for both at 77 K and 300 K exposure, to Mrad dose levels, and are thus potentially useful for electronics applications requiring simultaneous cryogenic temperature operation and significant total dose radiation exposure

X-ray total ionizing dose effects in both fully-depleted and partially-depleted SiGe HBT-on-SOI transistors are investigated at room and at cryogenic temperatures for the first time. Devices irradiated in grounded and forward-active mode configurations exhibit a different behavior depending on the collector doping of the device. The degradation produced by 10 keV x-rays is compared to previously reported 63 MeV proton results on the same fully-depleted SiGe HBT-on-SOI devices, showing decreased degradation for proton irradiation. Both collector and substrate bias are shown to affect the two-dimensional nature of the current flow in these devices, resulting in significant differences in the avalanche multiplication characteristics (hence, breakdown voltage) across temperature

We investigate the reliability issues associated with the application of CMOS devices contained within an advanced SiGe HBT BiCMOS technology to emerging cryogenic space electronics (e.g., down to 43 K, for Lunar missions). Reduced temperature operation improves CMOS device performance (e.g., transconductance, carrier mobility, subthreshold swing, and output current drive), as expected. However, operation at cryogenic temperatures also causes serious device reliability concerns, since it aggravates hot-carrier effects, effectively decreasing the inferred device lifetime significantly, especially at short gate lengths. In the paper, hot-carrier effects are demonstrated to be a stronger function of the device gate length than the temperature, suggesting that significant trade-offs between the gate length and the operational temperature must be made in order to ensure safe and reliable operation over typical projected mission lifetimes in these hostile environments.

We present the results of gamma irradiation on third-generation, 200 GHz SiGe HBTs. Pre- and post-radiation dc figures-of-merit are used to quantify the tolerance of the raised extrinsic base structure to Co-60 gamma rays for varying device geometries. Additionally, the impact of technology scaling on the observed radiation response is addressed through comparisons to second generation, 120 GHz SiGe HBTs. Comparisons to previous proton-induced degradation results in these 200 GHz SiGe HBTs are also made, and indicate that the STI isolation oxide of the device shows increased degradation following Co-60 irradiation. The EB spacer oxide, on the other hand, demonstrates increased susceptibility to proton damage. Low dose rate proton testing was also performed and indicate that although there is a proton dose rate effect present in these devices, it cannot fully explain the observed trends. Similar trends have previously been observed for buried oxides and isolation oxides in several MOS technologies and have been attributed to increased charge yield in these oxides for 1.2 MeV Co-60 gamma rays when compared to 63 MeV protons.

Total dose effects on silicon on insulator (SOI) UNIBOND wafers are studied via optical second harmonic generation (SHG). This technique is qualitatively compared with the pseudo-MOSFET technique for monitoring charges at the interfaces. Optical and electrical methods are combined to separate the contribution of the signal from each interface to the total SHG intensity. Radiation-induced oxide and interface traps increase the interface fields as determined from the SHG signals and the results are compared with electrical measurements.

Total ionizing dose effects on fully-depleted (FD) silicon-on-insulator (SOI) transistors are studied when the devices are operated in single gate (SG) and double gate (DG) mode. The devices exhibit superiority in mobility and drain current when operated in DG mode compared to SG mode. Moreover, the dc characteristics of DG operated device are less vulnerable to total dose radiation induced damage. In particular, radiation-induced interface traps have less electrical effect in DG mode operation.

1.8 MeV proton radiation-induced degradation in high electron mobility transistors with Si-doped Al/sub x/Ga/sub 1-x/N and thick GaN cap layers is studied up to a fluence of 1/spl times/10/sup 15/ protons/cm/sup 2/. The thick GaN cap layer reduces sheet charge modulation induced by the surface states, as it electrostatically separates the active device layers from the surface, thereby enhancing the device performance. The devices exhibit good tolerance up to 10/sup 14/ protons/cm/sup 2/, with displacement damage being the primary degradation mechanism. Charged defect centers introduced by proton radiation in the active device layers degrade carrier mobility and sheet carrier density. Proton radiation alters the barrier height at the Schottky gate and increases the resistance of the thin film structure.

We have studied the 1/f noise and total-dose response associated with the buried oxides (BOX) of fully depleted nMOS silicon-on-insulators (SOI) transistors. Silicon implantation in the BOX creates a higher density of oxygen vacancy-related defects that reduce the net oxide-trap charge, but increase the back-channel 1/f noise. The 1/f noise of MOSFETs fabricated on silicon-implanted SOI BOX shows little change after 1 Mrad(SiO/sub 2/) irradiation. Silicon implantation also creates shallow electron traps in the BOX, leading to large bias instabilities. Whether these traps are filled or empty does not significantly affect the 1/f noise. A detailed study of the 1/f noise, temperature dependence of charge trapping, and radiation response of these SOI nMOSFET transistors shows that charge exchange with shallow electron traps in the BOX occurs mostly via tunneling. Low frequency noise in the double-gate (DG) mode of device operation is also investigated, and found to help mitigate the 1/f noise in fully depleted SOI MOSFETs.

The degradation of AlGaN/AlN/GaN high electron mobility transistors due to 1.8-MeV proton irradiation was measured at fluences up to 3/spl times/10/sup 15/ cm/sup -2/. The devices have much higher mobility than AlGaN/GaN devices, but they possess similarly high radiation tolerance, exhibiting little degradation at fluences up to 1/spl times/10/sup 14/ cm/sup -2/. Decreased sheet carrier mobility due to increased carrier scattering and decreased sheet carrier density due to carrier removal are the primary damage mechanisms. The device degradation is observed as a decrease in the maximum transconductance, an increase in the threshold voltage, and a decrease in the drain saturation current.

Pseudo-metal-oxide-semiconductor (MOS) silicon-on-insulator (SOI) transistors are used to study the total ionizing dose response of buried oxides. The concentrations of radiation-induced oxide-trap and interface-trap charge are separated using midgap and dual-transistor charge separation analysis techniques. Dual-transistor analysis is shown to be especially well suited for charge separation of pseudo-MOSFETs (/spl Psi/-MOSFETs) because the electron conduction mode of this simple point-contact device resembles an nMOS transistor, and the hole conduction mode resembles a pMOS transistor. That this is a single device ensures that the dual-transistor assumption of equal oxide-trap charge in otherwise identical n and pMOS transistors is satisfied automatically. Both electron and hole conduction current-voltage (I-V) traces must extrapolate to a common, physically realistic midgap voltage; this is employed as a test for the self-consistency of /spl Psi/-MOSFET data. Charge separation performed using midgap and dual-transistor analyses show good agreement for the devices employed in this paper.

In this paper, we report experimental results and theoretical investigations of neutron irradiation-induced carrier-removal rate and mobility degradation in AlGaAs/GaAs heterojunction field-effect transistor structures. The measured two-dimensional (2-D) carrier removal rate of /spl sim/6.0 /spl times/ 10/sup -3/ is found to be consistent with a net (volume) introduction rate of /spl sim/20 cm/sup -1/ acceptor-like defects in the GaAs layer. Radiation-induced acceptors in the GaAs layer have the most significant effect on the 2-D electron concentration, whereas the acceptors in AlGaAs layer have negligible effect for neutron fluence up to 5 /spl times/ 10/sup 14/ cm/sup -2/. The measured 77-K mobility degradation, which is very sensitive to ionized impurity scattering, however, suggests that the introduction rate of the combined donor-like and acceptor-like defects is almost an order of magnitude higher (200 cm/sup -1/). The 300-K mobility, which is dominated by polar-optic phonon scattering, shows only marginal degradation.

Inverted metamorphic (IMM) solar cells are being pursued for space applications. This work examines their extended performance under key environmental conditions. Electron irradiation with 1 MeV electrons found 81% of the power remained after exposure to 1e15/ cm2 fluence. Test strings mounted on rigid panels were subjected to 11,000 thermal cycles without electrical degradation. Thermal soak testing at 250 °C identified 1% of efficiency loss, equivalent to production devices. No performance loss was found after 30 days of humidity exposure. These tests verify the integrity of IMM devices, while matching measurements by NREL confirm the quality of Spectrolab's IMM testing method.

Neutron irradiation effects on the I-V characteristics of AlGaAs-GaAs high electron mobility transistors and AlGaAs-InGaAs heterostructure insulated gate field-effect transistors are studied. Physical mechanisms responsible for the observed degradation of the device parameters are discussed.

Recent progress in III-V multijunction sp ace solar cell has led to Spectrolab’s GaIn P/GaAs/Ge triple-junction, XTJ, cells with average 1-sun efficiency of 29% (AM0, 28oC) for cell size ranging from 59 to 72-cm 2 . High-efficiency inverted metamorphic (IMM) multijunction cells are developed as the next space solar cell architecture. Spectrolab’s large-area IMM3J and IMM4J cells have achieved 33% and 34% 1-sun, AM0 efficiencies, respectively. The IMM3J and the IMM4J cells have both demonstrated normalized power retention of 0.86 at 5x10 14 e - /cm 2 fluence and 0.83 and 0.82 at 1x10 15 e - /cm 2 fluence post 1-MeV electron radiation, respectively. The IMM cells were further assembled into coverglass-interconnect-cell (CIC) strings and affixed to typical rigid aluminum honeycomb panels for thermal cycling characterization. Preliminary temperature cycling data of two coupons populated with IMM cell strings showed no performance degradation. Spectrolab has also developed semiconductor bonded technology (SBT) where high-performance component subcells were grown on GaAs and InP substrates separately then bonded directly to form the final multijunction cells. Large-area SBT 5-junction cells have achieved a 35.1% efficiency under 1-sun, AM0 condition. Keywords: space solar cells, III-V multijunction, inverted me tamorphic, semiconductor bonding technology.

High-efficiency Inverted Metamorphic (IMM) multi-junction solar cells are being developed at Spectrolab for use in space and near-space applications. Recently, large-area (26-cm2) IMM3J cells achieved a 1-sun, AM0 conversion efficiency of 32% with an open-circuit-voltage of 3.04 V, a short-circuit current-density of 16.7 mA/cm2, and a fill factor of 0.84. In addition, IMM4J cells (1-cm2) reached a 1-sun, AM0 conversion efficiency of 33%. The 4-junction cell achieved an open-circuit-voltage of 3.42 V, a short-circuit current-density of 15.8 mA/cm2, and a fill factor of 0.82. Both the inverted metamorphic 3J and 4J cells reveal excellent component subcell quantum efficiency. Improvements in crystal growth, as well as more optimal subcell current density balance, will further raise the 1-sun, AM0 efficiency of the 3J and the 4J IMM cells to 33% and 35% respectively. The latest status of the 72-cm2 XTJ (based on 150-mm Ge substrate) Supercells will also be discussed.

Multijunction solar cells have been a key enabler to Space Satellites in the past decade. Spectrolab has made major capital investment to improve the performance of the solar cells (W/m2) and reduce cost ($/W). The W/m2 improvement has been achieved by improving the efficiency of the solar cells (e.g. XTJ cell). The 29.5% efficiency XTJ cell has been qualified to AIAA-S-111–2005 standard. The $/W reduction has been achieved by qualifying the large format of the cells (e.g. UTJ and XTJ “LEONE”). The dimensions of the LEONE cells (53.3 cm2 to 59.65 cm2), also referred to as “1 per” cells, have been optimized to maximize utilization of the 100 mm wafer and achieve panel packing efficiency equal to or close to the heritage “2 per” cells from 100 mm wafer (26 cm2–32 cm2). UTJ LEONE cells are in orbit on board multiple LEO communication satellites. Insertion of these cell technologies followed a very rigorous qualification and reliability testing at cell, CIC and coupon level to mitigate any risk associated with the large area cell. The LEONE UTJ cell qualification program included thermo mechanical testing to 66,060 LEO and 15,549 GEO thermal cycles on multiple coupons; and radiation testing on bare cells. Inverted and normal gradient ESD testing was performed on CICs and multiple coupons to mitigate potential risk with use of large area cells on high voltage arrays. The ESD testing on coupons was performed up to a differential voltage of 130V at 1.2 A without occurrence of any permanent sustained arcs. To further reduce the $/W, Spectrolab is now transitioning to the 150 mm wafer fab line leading to the insertion of the 72.44 cm2 XTJ “SuperCell” in the 3rd quarter of 2012. This presentation will discuss the details of the qualification and reliability tests and test results on LEONE cells. The presentation will also discuss the qualification test and insertion plan for the XTJ SuperCell.

Spectrolab successfully completed the qualification of its latest and final triple junction space solar cell, 30% class XTJ (neXt Triple Junction), per AIAA S-111-2005 and Spectrolab test standards. The final qualification and characterization test results are presented in this paper. XTJ exhibits a 4.2 % power gain over Spectrolab's current space PV, UTJ, at both beginning of life and end of life. Moreover, nearly 3% lower solar absorptance of XTJ allows for a cooler operating temperature in a typical GEO mission. XTJ showed excellent front and backside welding contact integrities, insensitivity to ESDS, and negligible loss from humidity and GEO thermal cycle tests. Currently Spectrolab's large area XTJ (59.65cm2) is undergoing qualification per Spectrolab specified test standards.

Spectrolab presents the qualification status of its latest triple junction space solar cell, neXt Triple Junction (XTJ). The beginning of life efficiency averages 29.9% at maximum power (AM0, 28°C, 135.3 mW/cm2). The qualification in progress complies with the AIAA S-111-2005 standards for bare cell, CIC, and coupon level tests. Thermal cycle GEO coupons built for engineering confidence prior to the qualification showed excellent mechanical and electrical performance. Interim qualification status and test results are discussed.

Spectrolab presents its next production GaInP/GaAs/Ge space triple junction solar cell, the XTJ space solar cell, averaging 29.8% efficiency at maximum power (AM0, 28°C, 135.3 mW/cm2) at beginning-of-life (BOL) testing of large populations (845 cells) of large-area solar cells without coverglass. Bare cells from this population with area of 26.62 cm2 have been tested to a maximum efficiency of 31.1% under the same AM0 testing. Additional optical and electrical performance characterization will be presented. XTJ is more than a BOL power improvement over heritage products. Bare cell radiation testing shows power retention at max power (NP mp ) of 0.89 and 0.84 after irradiation with 1-MeV energy electrons to a fluence of 5e14 cm−2 and 1e15 cm−2, respectively. Environmental degradation testing of XTJ parts shows only 1.7% degradation for more than 4000 hours at 250°C and no degradation after 90 days at 95% r.h. and 45°C. Together these characteristics enable XTJ to be a 7% improvement in end-of-life cost of power on space flight panel over Spectrolab's 28% BOL efficient UTJ. Finally, XTJ engineering confidence thermal cycle testing and qualification status to the AIAA S-111-2005 standard will be elaborated.

In this paper we compare 10 keV X-ray and 63 MeV proton radiation effects on 4H-SiC vertical trench JFET power transistors. The schematic cross-section of the 4H-SiC depletion-mode vertical trench JFET was investigated. For a direct comparison, total dose levels were held constant between the two radiation sources. The significant differences in device response for the two different radiation sources, and the isochronal annealing effects on proton-irradiated devices, are presented in this paper.

The effects of proton irradiation on the performance of key devices and mixed-signal circuits fabricated in a SiGe BiCMOS IC design platform and intended for emerging lunar missions are presented. High-voltage (HV) transistors, SiGe bandgap reference (BGR) circuits, a general-purpose high input impedance operational amplifier (op amp), and a 12-bit digital-to-analog converter (DAC) are investigated. The circuits were designed and implemented in a first-generation SiGe BiCMOS technology and were irradiated with 63 MeV protons. The degradation due to proton fluence in each device and circuit was found to be minor, suggesting that SiGe HBT BiCMOS technology could be a robust platform for building electronic components intended for operation under extreme environments.

The authors reported the floating body effects in 90nm partially-depleted, strained-silicon CMOS on SOI devices operating down to cryogenic temperatures. These devices also exhibit immunity to X-ray and proton irradiation without process hardening (Appaswamy et al, 2006) and thus are potentially suitable for space applications. One-to-one comparisons are made to conventional unstrained CMOS on SOI devices from the same 90 nm technology node

The effects of 63 MeV proton irradiation on 90 nm strained silicon CMOS on insulator is examined for the first time. The devices show no observable degradation in DC performance up to an equivalent total dose of 600 krad(Si). The performance of the strained pFETs is identical to unstrained pFETs and demonstrates the immunity of strain to displacement damage. There is no significant enhancement observed in back channel leakage for the maximum dose. Passive exposure to 2 Mrad(Si) using 4 MeV protons doesn't induce any significant performance degradation.

In this article, total dose effects on thin gate oxide, partially depleted SOI transistors are presented. The thin gate oxide is minimally affected by the radiation, while trapped holes in the buried oxide suppress the second g/sub m/ peak by reducing the float body volume. Ultrathin tunneling oxides enable GIFBE and render the front channel of partially depleted transistors more sensitive to carrier trapping in the BOX. The devices recover during isochronal annealing, approaching the pre-irradiation characteristics at temperatures near 300 /spl deg/C.

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