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The behavior of an off-state leakage current induced by heavy-ion irradiation in deep-submicrometer NMOSFETs is comprehensively investigated by 3-D simulation in this paper. The results show that the off-state drain current is increased, which is mainly due to the positively charged damage region generated by the heavy-ion strike in the shallow-trench isolation (STI) region. As the channel length scales down, the off-state leakage collapse becomes more severe. The dependence of the off-state leakage current on the device channel length and width is studied, which gives the location of the most critical physical damage region in the STI trench oxide. Moreover, the impact of the gate bias during exposure to heavy ions on the device off-state behavior is also analyzed, indicating that a low operating voltage is beneficial to the circuit radiation hardening. At last, to suppress the off-state leakage collapse, some possible solutions are proposed.

In this paper, we investigate the combined effects of total ionizing dose (TID) and negative bias temperature instability (NBTI) on deep sub-micron pMOSFETs. It is found that the high temperature of the NBT stress induces an annealing effect by removing part of the radiation-induced positive charges. If we choose a relatively low temperature to avoid the annealing effect, a remarkable radiation acceleration effect on device degradation is observed and the lifetime of pMOSFETs significantly reduces due to more radiation-induced new hole traps in the oxide. However, the acceleration effect seems independent of the oxide electric field during NBT stress. The work in this paper indicates that it is important to choose proper NBT stress conditions if we use NBTI to predict the lifetime of the pMOSFETs which operate in the radiation environments.

The deteriorated radiation effects of very deep-sub-micron (VDSM) MOS transistors with multi-finger are experimentally investigated for the first time. The results show that due to the interaction between reverse narrow channel effect and radiation induced edge effect, multi-finger transistors are more sensitive to radiation in comparison with standard MOSFETs. Larger threshold-voltage shift and higher leakage current are observed. The mechanisms responsible for the effects are briefly discussed. The results demonstrate that special radiation hardening technology should be adopted for multi-finger transistors operating in the radiation environment.

ZnO films are firstly prepared on Si substrates by pulsed laser deposition (PLD) technique and then the Ga 2 O 3 films are deposited on ZnO/Si substrates by magnetron sputtering system. The low-dimensional GaN nanostructured materials are obtained by ammoniating the Ga 2 O 3 /ZnO films from 850 to 1000 °C for 15 min in a quartz tube. X-ray diffraction (XRD), scanning electron microscope (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared spectrophotometer (FTIR) and photoluminescence (PL) are used to analyze the structure, morphology and optical properties of as-grown samples. The results show that their properties are investigated particularly as a function of ammoniating temperatures. Large quantities of high-quality GaN nanowires are successfully fabricated at 900 °C with lengths of about tens of micrometers and diameters ranging from 30 to 120 nm, which could supply an attractive potential to harmonically incorporate future GaN optoelectronic devices into Si-based large-scale integrated circuits. Finally, the growth mechanism is also briefly discussed.

ZnO thin films with different thickness (the sputtering time of ZnO buffer layers was 10 min, 15 min, 20 min, and 25 min, respectively) were first prepared on Si substrates using radio frequency magnetron sputtering system and then the samples were annealed at 900 °C in oxygen ambient. Subsequently, a GaN epilayer about 500 nm thick was deposited on ZnO buffer layer. The GaN/ZnO films were annealed in NH 3 ambient at 950 °C. X-ray diffraction (XRD), atom force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to analyze the structure, morphology, composition and optical properties of GaN films. The results show that their properties are investigated particularly as a function of the sputtering time of ZnO layers. For the better growth of GaN films, the optimal sputtering time is 15 min.

ZnO thin films were first prepared on Si(111) substrates using a radio frequency magnetron sputtering system. Then the as-grown ZnO films were annealed in oxygen ambient at temperatures of 700, 800, 900, and 1000°C , respectively. The morphologies of ZnO films were studied by an atom force microscope (AFM). Subsequently, GaN epilayers about 500 nm thick were deposited on the ZnO buffer layers. The GaN/ZnO films were annealed in NH3 ambient at 900°C. The microstructure, morphology and optical properties of GaN films were studied by x-ray diffraction (XRD), AFM, scanning electron microscopy (SEM) and photoluminescence (PL). The results are shown, their properties having been investigated particularly as a function of the ZnO layers. For better growth of the GaN films, the optimal annealing temperature of the ZnO buffer layers was 900°C.

A new method using two-step growth technology to successfully synthesize high-quality single crystalline GaN nanobelts was employed in this paper. This growth method is applicable to continuous syn...

Large quantities of GaN nanorods have been successfully synthesized on Si(1 1 1) substrates by magnetron sputtering through ammoniating the Ga 2 O 3 /ZnO films at 950 °C in a quartz tube. The GaN nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), a field-emission transmission electron microscope (FETEM), a Fourier transform infrared (FTIR) spectrophotometer and a fluorescence spectrophotometer. The results show that the nanorods have pure hexagonal GaN wurtzite structure, with lengths of about several micrometers and diameters of about 200 nm. The clear lattice fringes demonstrate that the synthesized nanorods are single-crystal GaN. The FTIR spectrum further confirms that the GaN is obtained under this condition. The representative photoluminescence spectrum at room temperature exhibited a strong emission peak at 375.7 nm and two weak emission peaks at 436.2 and 475.5 nm. The GaN nanorods show a very good emission property, which will have a good advantage for applications in laser device using one-dimensional structures. Finally, the growth mechanism is also briefly discussed.

GaN nanowires were successfully synthesized on Si(111) substrates by ammoniating the Ga 2 O 3 /ZnO films at 900 °C. The structure, morphology and optical property of the as-prepared GaN nanowires were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared spectrum (FTIR) and fluorescence spectrophotometer. The results show that the GaN nanowires have a hexagonal wurtzite structure with lengths of about several micrometers and diameters ranging from 30 nm to 120 nm. The representative photoluminescence spectrum at room temperature exhibited a strong emission peak at 374.1 nm and two weak emission peaks at 437.4 nm and 473.3 nm. Finally, the growth mechanism is also briefly discussed.

As-grown ZnO thin films are annealed in O 2 ambient for 15 min at the temperature of 700 °C, 800 °C, 900 °C and 1000 °C, respectively. Then the Ga 2 O 3 thin films are deposited on ZnO/Si(111) substrates by sputtering Ga 2 O 3 target in a JCK-500A radio frequency magnetron sputtering system. The low dimensional GaN nanostructured materials are obtained on Si substrates by ammoniating the Ga 2 O 3 /ZnO films at 950 °C for 15 min in a quartz tube. X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectrophotometer (FTIR) and photoluminescence (PL) are used to analyze the structure, morphology and optical properties of GaN nanostructured films. The results show that their properties are investigated particularly as a function of annealing temperature of ZnO layer. The mechanism is also briefly discussed.

GaN nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating Ga2O3/ZnO films at 950 °C in a quartz tube. The GaN nanorods are characterized by X-ray diffraction, scanning electron microscopy, field-emission transmission electron microscopy, X-ray photoelectron spectroscopy and fluorescence spectrophotometry. The results show that the nanorods have a pure hexagonal GaN wurtzite structure with lengths of about several micrometers and diameters of about 200 nm, and the growth direction of the GaN nanorods is parallel to the (101) plane. The photoluminescence spectrum indicates that the nanorods have a good emission property. Finally, the growth mechanism is also briefly discussed.

ZnO thin films were prepared on Si(111) substrates by pulsed laser deposition (PLD). Then, the samples were annealed at different temperatures in NH3 ambient and their properties were investigated particularly as a function of annealing temperature. The structure, morphology, and optical properties of ZnO films were studied by x-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), scanning electron microscope (SEM), and photoluminescence (PL). The results show that the increase of annealing temperature makes for the improvement in the crystal quality and surface morphology below the temperature of 650°C. However, when the annealing temperature is above 650°C, the ZnO films will volatilize and, especially at 750°C, ZnO will volatilize completely.

Background: In Streptococcus mutans, ComCDE, a peptide-induced two-component signal transduction system, forms a closed signal transduction, and even if difunctional ComE closes this signal at its headstream to avoid its infinite amplification, it is not enough for ComE to work in a concentration-dependent manner. CslAB has a chance to regulate ComCDE by controlling extracellular competence-stimulating peptide (CSP) concentration through its processing and secretion. Objectives: To first confirm the binding properties of cslAB promoter (PcslAB) with ComE, then to uncover in vivo need of cslAB expression, and finally to unveil the role of CslAB. Materials and Methods: Electrophoretic mobility shift assay was used to confirm the binding properties of PcslAB with ComE. In vivo cslAB transcription was detected by β-galactosidase activity because its gene has been fused to cslAB operon, and finally the role of CslAB was reviewed. Results: PcslAB is a weak promoter responding to ComE and its binding appears to be negative cooperative. Although PcslAB is partially controlled by ComCDE, it can respond to ComCDE regulation. Supported by the obtained molecular evidence, CslAB acts as a stabilizer of ComCDE signal on the patterns of its expression. Conclusions: PcslAB is partially controlled by ComCDE. CslAB is a stabilizer of ComCDE signal to ensure that ComE works in a concentration-dependent manner.

ZnO thin films were firstly prepared on Si(111) substrates using radio frequency magnetron sputtering system. Then the samples were annealed at different temperature in oxygen ambient and their properties were investigated particularly as a function of annealing temperature. The microstructure, morphology and optical property of ZnO films were studied by XRD, AFM, FTIR and PL. The results show that the increase of annealing temperature leads to the improvement in the crystal quality.

ZnO thin films were deposited on n-Si (111) at various substrate temperatures by pulsed laser deposition (PLD). X-ray diffraction (XRD), photoluminescence (PL), Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscopy (SEM) were used to analyze the structure, morphology, and optical property of the ZnO thin films. An optimal crystallized ZnO thin film was obtained at the substrate temperature of 600°C. A blue shift was found in PL spectra due to size confinement effect as the grain sizes decreased. The surfaces of the ZnO thin films were more planar and compact as the substrate temperature increased.

A simple method using two-step growth technology to successfully synthesize the high-quality single crystalline GaN nanobelts was employed in this paper. The as-prepared products are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results of XRD and the selective area electron diffraction (SAED) patterns indicate that the reflections of the samples can be indexed to the hexagonal GaN phase with single-crystal structure. From the SEM morphology, we can see that the width of the nanobelts is about 800 nm, and the ratio of thickness to width is about 1/10. The maximum length is up to several tens of micrometers. In the HRTEM image, the clear lattice fringes indicate the growth of good-quality hexagonal single-crystal GaN nanobelts. Finally, the growth mechanism is also briefly discussed.

GaN nanowires are successfully synthesized on Si(111) substrates through ammoniating the Ga2O3/ZnO films by radio frequency magnetron sputtering system. X-ray diffraction (XRD), scanning electron microscope (SEM), field-emission transmission electron microscope (FETEM), and Fourier transform infrared spectroscopy (FTIR) are employed to examine the structural and surface morphological properties of the as-prepared GaN nanowires. The results show that the single-crystal GaN nanowires have a hexagonal wurtzite structure with lengths of about several micrometers and diameters ranging from 60 to 160 nm, which is conducive to the application of nanodevices. The assistance of the volatilization of ZnO buffer layer has a great impact on the growth of GaN nanowires. The growth mechanism is also briefly discussed.

The GaN nanowires were successfully synthesized on Si(111) substrates by ammoniating the Ga2O3/ZnO films at 900 °C. The structure and morphology of the as-prepared GaN nanowires were studied by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM) and field-emission transmission electron microscopy (FETEM). The results show that the single-crystal GaN nanowires have a hexagonal wurtzite structure with lengths of about several micrometers and diameters ranging from 30 nm to 120 nm, which are conducive to the application of nanodevices. Finally, the growth mechanism is also briefly discussed.

GaN nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating the Ga 2 O 3 /ZnO films at 950 °C in a quartz tube. The GaN nanorods have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared (FTIR) system and fluorescence spectrophotometer. The results show that the nanorods are pure hexagonal GaN wurtzite structure with lengths of about several micrometers and diameters ranging from 100 nm to 750 nm, and the growth direction of GaN nanorods is perpendicular to (101) plane. The photoluminescence (PL) spectrum indicates that the good emission property for the nanorods. Finally, the growth mechanism is also briefly discussed.

The paper describes the parasitic structures of MOS transistors in SOI CMOS ICs at first. Then the influences of the parasitic structures on single particles radiation effect of MOS transistors in SOI CMOS ICs are presented. Finally the hardness methods of single event effects resulted by the parasitic structures of MOS transistors are given and the estimate about their excellence is made out.

In this paper, we have focused our attention on DC characteristics degradation of 0.18 ?m MOSFETs after 10-MeV proton irradiation. It is shown that the threshold voltage shift, the transconductance degradation and the saturation drain current decrease are lager in PMOSFETs, while small effects are exhibited in NMOSFETs. From the analysis, it is concluded that the basic damage mechanism is not ascribed to the gate oxide and the isolation. The origin of the observed changes is due to the damage in spacer oxides of the MOSFETs. The mechanism involved is that the energetic protons incident on the spacer region lose their energy to displace the atoms, give rise to many defects, and create a disordered region (displacement damage region), where many defects and traps can capture positive charges to make the static characteristics degraded. Therefore, it is pointed out that the sidewalls are one of sensitive regions for irradiation hardness.

A new method using defect-pit-assisted growth technology to successfully synthesize the high-quality single crystalline GaN nanostructures by ammoniating Ga(2)O(3) films was proposed in this paper. During the ammoniating process, the amorphous middle buffer layer may unavoidably produce some defects and dislocations. Some defect pits come out, which have the lowest surface energy and can subsequently be used as a mask/template or act as potential nucleation sites to fabricate the GaN actinomorphic nanostructures. The as-prepared products are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results indicate that all the reflections of the samples can be indexed to the hexagonal GaN phase and the clear lattice fringes in HRTEM further confirm the growth of high-quality single-crystal GaN nanostructures. The SEM images show that the nanostructures have been realized under different experimental conditions exhibiting different shapes: nanowires, nanorods, and nanobelts. No particles or other nanostructures are found in the SEM study, demonstrating that the product possesses pure nanostructures. These nanostructures show a very good emission peak at 366 nm, which will have a good advantage for applications in laser devices using one-dimensional structures. Finally, the growth mechanism is also briefly discussed.

In this paper, the total ionizing dose (TID) and single-event effect (SEE) in vertical channel double-gate (DG) nMOSFETs are comprehensively investigated. Due to the vertical channel structure and the excellent gate control capability, the vertical channel DG transistor is relatively resistant to TID and transient ionization effect. However, the dc characteristics of vertical channel DG device are very sensitive to permanent damage induced by a few ions hitting the device. The on-state current and transconductance of the vertical channel DG MOSFETs show significant degradation after exposure to heavy ions, which is attributed to the formation of displacement damage in the channel. As the device feature size scales down to the deca-nanometer regime, the influence of permanent damage induced by a few ions striking the device static performance cannot be ignored and should be seriously considered in radiation-hardened technologies.

This paper mainly reports the permanent impact of displacement damage induced by heavy-ion strikes on the deep-submicron MOSFETs. Upon the heavy ion track through the device, it can lead to displacement damage, including the vacancies and the interstitials. As the featured size of device scales down, the damage can change the dopant distribution in the channel and source/drain regions through the generation of radiation-induced defects and thus have significant impacts on their electrical characteristics. The measured results show that the radiation-induced damage can cause DC characteristics degradations including the threshold voltage, subthreshold swing, saturation drain current, transconductance, etc. The radiation-induced displacement damage may become the dominant issue while it was the secondary concern for the traditional devices after the heavy ion irradiation. The samples are also irradiated by Co-60 gamma ray for comparison with the heavy ion irradiation results. Corresponding explanations and analysis are discussed.

A radiation-induced leakage current model in deep submicron bulk silicon N-channel metal-oxide-semiconductor field effect transistor (NMOSFET) is proposed in this paper for circuit simulations. The model takes into account the impact of the substrate doping concentration, the angle of shallow trench isolation (STI) region, and the junction depth of source/drain, which can predict the off-state leakage current of the NMOSFET with STI region irradiated at different radiation doses. The model is verified by comparing with the experimental results. The model can be easily implemented into the circuit simulator to evaluate the impact of total ionizing dose effect on the performance of circuit.

The total ionizing dose effects of novel vertical channel double-gate nMOSFETs (DGMOS) are experimentally investigated and compared with conventional planar nMOSFETs firstly in this paper. The radiation-induced off-state leakage current and subthreshold slope are greatly suppressed in vertical DGMOS devices compared with conventional nMOSFETs. The performance of vertical DGMOS devices under irradiation does not change apparently even when the dose is up to 1 Mrad(Si), which is attributed to its unique device structure for separating the channel from the thick oxide isolation region and preventing the formation of a leakage path. The results indicate that the vertical channel device structure is a promising candidate for future space applications.

The dc characteristics degradation of 0.18 μm metal-oxide-semiconductor field effect transistors (MOSFETs) after 10 MeV proton irradiation is comprehensively investigated in this paper. The measured results show that the off-state drain current is increased in N-channel MOSFETs, which is due to the turn on of the parasitic transistors induced by the shallow trench isolation regions. While in P-channel MOSFETs, the threshold voltage increase (absolute value), the transconductance degradation, and the saturation drain current decrease are observed. From the analysis, it is concluded that the basic damage mechanism is not ascribed to the gate oxide and the isolation region. The origin of the observed changes may be mainly due to the damage in the spacer oxides of the transistors. In order to verify the assumption, the leakage current passing through the spacer between the gate and the drain is measured before and after irradiation with floated source/substrate and grounded drain. We find that the leakage cur...