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The impact of 63.3 MeV proton and 10 keY x-ray irradiation on the DC and AC performance of complementary (npn + pnp) 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. Index Terms--C-SiGe, heterojunction bipolar transistors, radiation effects, SiGe HBT, silicon-on-insulator, SOI, TCAD.

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 ([L.sub.SD] and [L.sub.G]) 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. Index Terms--Bulk traps, buried-channel, displacement damage, MODFET, radiation effects, SiGe, silicon-germanium, strain.

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(Si[O.sub.2]) and 5400 krad(Si[O.sub.2]). 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. Index Terms--BiCMOS analog integrated circuits, heterojuction bipolar transistors, ionization damage, proton radiation effects, SiGe, SiGe HBTs, X-rays.

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(Si[O.sub.2]). 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(Si[O.sub.2]) are presented, showing no degradation in performance metrics under two low current density bias configurations. Index Terms--Complementary bipolar, heterojunction bipolar transistors, radiation effects, SiGe HBT, silicon-germanium.

Proton and X-ray irradiation effects are investigated in 0.35 [micro]m conventional, annular, and ringed-source radiation-hardening-by-design (RHBD) CMOS devices. Transistors were irradiated with protons at both 300 K and 77 K. Radiation-induced oxide trapped charges in the shallow trench isolation (STI) oxide deplete the p-substrate and effectively shunt the source and drain, inducing off-state leakage. Without the STI, RHBD nFETs exhibit no radiation-induced off-state shunt leakage currents for devices irradiated at both 300 K and 77 K. Conventional 0.35 [micro]m pFETs were not degraded by proton irradiation, since the leakage path cannot be formed in the n-well. A simple CMOS logic inverter shows no degradation in output voltage after proton irradiation for all tested temperature and bias conditions. More advanced 130 nm node nFETs show less TID sensitivity to STI leakage due possibly to the smaller physical STI volume and/or additional doping located on the STI sidewall. Index Terms--CMOS, cryogenic, cryogenic temperatures, displacement damage, off-state leakage current, radiation hardening by design (RHBD), shallow trench isolation, shallow trench isolation (STI), TID.

Using mixed-mode annealing to help evaluate the responses of modern bipolar transistors, we compare the damage processes associated with X-ray irradiation-induced and hot carrier-induced damage in SiGe HBTs. Stress and radiation measurements indicate that the by-products of both X-ray irradiation-induced and hot carrier-induced trap reactions are identical. We use calculations to better understand the operative damage mechanisms, and find that a hydrogen reaction-diffusion model can predict the observed characteristics of our measurements. Calculations indicate that the transport of hydrogen molecules inside the emitter-base oxides determines the trap generation and recovery processes. Index Terms--Mixed-mode anneal, mixed-mode stress, reaction-diffusion model, SiGe, SiGe HBTs, silicon-germanium, thermal anneal, X-ray irradiation.

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. Index Terms--Interface trapped charge, irradiation, low temperature, proton irradiation, SiGe HBT.

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. Index Terms--CMOS, cryogenic, GIDL, off-state leakage current, shallow trench isolation, STI, total dose radiation effects.

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. Index Terms--Dose enhancement, hardness assurance, low-frequency noise, silicon-germanium (SiGe), hetero-junction bipolar transistor, total ionizing dose.

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. Index Terms--Heterojunction bipolar transistors, radiation effects, SiGe HBT, silicon-on-insulator technology, SOI, TCAD.

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. Index Terms--EB spacer, ELDRS, gamma radiation, proton radiation, radiation sources, SiGe, SiGe HBT, shallow trench isolation, technology scaling.

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 x [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. Index Terms--Gallium alloys, modulation-doped field effect transistors (MODFETs), proton radiation effects.

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. Index Terms--Charge coupling, double gate, fully-depleted (FD) silicon-on-insulator (SOI) transistors, total dose effects.

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. Index Terms--Pseudo-MOSFET, radiation effects, second harmonic generation (SHG), silicon on insulator (SOI), total dose, UNIBOND.

The degradation of AlGaN/AlN/GaN high electron mobility transistors due to 1.8-MeV proton irradiation was measured at fluences up to 3 x [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 x [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. Index Terms--Gallium alloys, MODFETs, proton radiation effects.

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 ~6.0 x [10.sup.-3] is found to be consistent with a net (volume) introduction rate of ~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 x [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. Index Terms--Carrier removal in heterojunction structures, high electron mobility transistor (HEMT), mobility degradation, MODFET, neutron irradiation.

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. Index Terms--High electron mobility transistors (HEMT), heterostructure insulated gate field-effect transistor (HIGFET), MODFET, neutron irradiation.

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. [ABSTRACT FROM AUTHOR]

1.8 MeV proton radiation-induced degradation in high electron mobility transistors with Si-doped AIxGa1-xN and thick GaN cap layersis studied up to a fluence of 1 × 1015 protons/cm2 . 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 1014 protons/cm2, 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. [ABSTRACT FROM AUTHOR]