Anomalous radiation effect in p-channel MOSFET's under electron irradiation

An anomalous shift in the gate threshold voltage of high-transconductance p-channel MOSFET's has been observed during exposure to space-like radiation of 2 × 10¹²electrons/cm²that is two and one half to three times its saturation value at 2 × 10¹⁴electrons/cm²and is five to seven times its pre-irradiation value.     

Neutral electron trap generation under irradiation in reoxidizednitrided gate dielectrics

In this study we report for the first time results on neutral electron trap generation in reoxidised nitrided oxide dielectrics under various radiation doses and bias conditions and compare the results with the conventional oxides. We see very little electron trap creation in RNO dielectrics for radiation doses up to 5 Mrad (Si) and for bias fields up to ±2.5 MV/cm. We explain our results in RNO and oxide dielectrics using a three step defect creation model     

Degradation of InGaAs/InP single heterojunction bipolar transistors under high energy electron irradiation

The d.c. characteristics of InGaAs/InP single heterojunction bipolar transistors (SHBTs) were studied for the first time under high energy (1 MeV) electron radiation of cumulative dose up to 5.4×10¹⁵ electrons/cm². No degradation was observed for electron doses below 10¹⁵/cm². For electron doses greater than 10¹⁵/cm² the following degradation effects were observed: (1) decrease in collector current; (2) decrease in current gain up to 50%; (3) an increase in collector saturation voltage by 0.2–0.8 V depending on base current; and (4) increase in output conductance. The degradation of collector current and current gain are thought to be due to increased recombination caused by radiation-induced defects in the base–emitter junction. The increase in collector saturation voltage is attributed to an increase in emitter contact resistance after irradiation. The increase in the avalanche multiplication in the reverse biased base–collector junction caused by radiation induced defects is believed to be responsible for increased output conductance after irradiation.     

Degradation of DC characteristics of InGaAs/InP singleheterojunction bipolar transistors under electron irradiation

The effects of high-energy (~1 MeV) electron irradiation on the dc characteristics of InGaAs/InP single heterojunction bipolar transistors (SHBT's) are investigated. The device characteristics do not show any significant change for electron doses <10¹⁵/cm². For higher doses, devices show a decrease in collector current, a degradation of common-emitter current gain, an increase in collector saturation voltage and an increase in the collector output conductance. A simple SPICE-like device model is developed to describe the dc characteristics of SHBT's. The model parameters extracted from the measured dc characteristics of the devices before and after irradiation are used to get an insight into the physical mechanisms responsible for the degradation of the devices     

Defect-engineering in SiC by ion implantation and electron irradiation

Three examples are given, which show that ion implantation and electron irradiation can drastically modify the electrical properties of SiC and SiC-based MOS capacitors. (1) It is demonstrated that sulphur ions (S⁺) implanted into 6H-SiC act as double donors with ground states ranging from 310 to 635 meV below the conduction bandedge. (2) Co-implantation of nitrogen (N⁺) - and silicon (Si⁺) - ions into 4H-SiC leads to a strong deactivation of N donors. Additional experiments with electron (e⁻)-irradiated 4H-SiC samples (E(e⁻) = 200 keV) support the idea that this deactivation is due to the formation of an electrically neutral (N_x-V_C, y)-complex. (3) Implantation of a surface-near Gaussian profile into n-type 4H-SiC followed by a standard oxidation process leads to a strong reduction of the density of interface traps D_it close to the conduction bandedge in n-type 4H-SiC/SiO₂ MOS capacitors.     

电子束照射下金纳米微粒的接合

纳米微粒由于其独特的物理、化学性能而受到世界范围的广泛关注。使用金属、合金、半导体和陶瓷纳米微粒来制备功能材料,如陶瓷超塑性材料,一直是科学家们研究的焦点。为了了解这些纳米微粒不同寻常的特性,开发将这些纳米微粒制成块体功能材料的方法,必须对纳米微粒的接合行为进行研究。用电子束照射的方法在HRTEM中动态观察A1/A1纳米微粒的接合过程作者已有报道[1～3],本文研究了金纳米微粒的迁移、旋转和接合,并对其接合机理进行分析讨论。具有直径为1～6纳米的金纳米微粒是由氩离子束溅射技术制备的[3]。金纳米微粒放置在厚度大约为20…     

Comparison of neutron and electron irradiation for controlling IGT switching speed

Neutron irradiation (NI) and electron irradiation (EI) techniques are used to control carrier lifetime in insulated-gate transistors (IGT's). The two techniques are compared on the basis of switching speed/forward voltage drop tradeoff, long-term stability, and practicality. It is found that the nature of the crystal defect responsible for lifetime reduction is the same for both NI and EI techniques. Based upon this finding, EI is recommended as the preferred technique because it offers reduced process complexity and the ability to irradiate pretested devices mounted on headers.     

Effects of electron and gamma-ray irradiation on CMOS analog image sensors

Changes in the average brightness and non-uniformity of dark output images, and quality of the pictures captured under natural lighting from the black and white (B&W) complementary metal oxide semiconductor (CMOS) analog image sensors irradiated at different electron doses have been studied in comparison to those from the γ-ray irradiated sensors. For the electron-irradiated sensors, picture becomes blurry at 1.0 kGy, average brightness increases sharply and bright strips appear only at 0.6 kGy, non-uniformity increases obviously with an increasing dose and reaches maximum at 1.0 kGy. But for the γ-irradiated sensors, pictures and dark output images are nearly the same as that from the unirradiated CMOS image sensor up to 1.2 kGy, pictures become blurry above 1.8 kGy, and average brightness increases sharply above 1.4 kGy. Electron radiation damage is much more severe than γ-ray radiation damage for the CMOS image sensors. A possible explanation is presented.     

Measurement and simulation of GaAs FET's under electron-beam irradiation

Injection of 15-kV electrons into gallium arsenide field-effect transistors leads to static current gains in excess of 10⁷. Such gains are well above the 3600 gain expected from electron-hole pair production. A two-dimensional computer simulation has been extended to include electron-beam production of excess carriers at arbitrary points in the device structure. The resulting redistribution of potentials is shown to predict an increase in the effective channel thickness. The corresponding increase in drain current is in good agreement with the experimental measurements.     

Effects of electron and proton irradiation on embedded SiGe source/drain diodes

The performance degradation of the I/V and C/V characteristics of Si_1−xGe_x S/D diodes irradiated by 2-MeV electrons and 70-MeV protons was investigated. After irradiation, the reverse current increases, while the forward current and reverse capacitance decrease. Based on considerations of the damage factor and coefficient for different fluences and radiation sources, the radiation damage becomes smaller with increase in germanium content. Also, for proton irradiation, the damage is about three orders of magnitude larger than for electrons due to the difference of particle mass and collision probability to produce displacement damage.     

Effect of electron irradiation on optical and photoelectric properties of microcrystalline hydrogenated silicon

Semiconductors - The effect of irradiation with 40 keV electrons on the spectral dependence of the absorption coefficient and on the conductivity and photoconductivity of μc-Si:H was studied....     

A study of electron transition in the energy gap of SI-GaAs with photoconductivity spectra and under α-particle irradiation

The aim of the present work is to study the density of electron transitions inside the energy gap of SI-GaAs at various temperatures and under α-particle irradiation at 300 K. The photocurrent as a function of photon energy from 1.35 to 1.80 eV, for each temperature, was measured in the temperature range from 180 to 300 K. From the spectra analysis for each temperature, three peaks were found. The energy that corresponds to the peaks as a function of temperature was plotted. The temperature and the irradiation strongly affect the value of the peaks, which is related to the number of transitions of the electrons inside the energy gap. As the temperature decreases, the peaks follow the same change. After irradiation, the values of the peaks decrease for all temperatures and this decrease is more intense for the P3 peak.     

单脉冲激光对CCD探测器的硬损伤及损伤概率

在纳秒激光脉冲辐照下,随着CCD探测器损伤程度的加深,成像系统输出画面中先后出现点损伤、白线损伤以及完全失效等现象,且损伤阈值呈现出概率分布特性。实验激光波长为1 064 nm,首先采用n-on-1辐照模式,研究CCD探测器在不同损伤程度下的损伤现象,从器件工作原理的角度分析各种现象出现的机理。利用光学显微镜观察样品的损伤形貌,发现探测器的损伤部位从内部材料开始,逐渐发展到位于表面的微透镜结构。接下来,采用1-on-1辐照模式测量了点损伤和完全失效阶段的激光能量密度阈值,并以损伤概率的形式进行描述,得到实验样品的完全失效阈值在100 mJ/cm2左右。     

K0.3MoO3电子辐照下有序-无序转变及恢复

准一维K0.3MoO3蓝青铜中的电荷密度波(CDW)失稳一直是凝聚态物理研究的热点之一.在180K温度附近K0.3MoO3发生晶格畸变伴随着电荷发生空间周期性调制,形成所谓的CDW.当调制波矢量q=2KF时,布里渊区将与费米面套叠而打开一个Peierls能隙,导致体系从导体向半导体或绝缘体的转变,即Peierls相变.Peierls失稳是低维系统的特有行为,具有强烈的维度依赖性,非常敏感于元素掺杂和各种机制产生的缺陷.电子辐照产生的结构变化对于CDW材料的Peierls相变温度和Peierls能隙的形成有很强的影响,强的电子辐照使Peierls相变温度下降.且随着辐照剂量的增大,Peierls能隙甚至被抹平.     

The effects of electron irradiation and thermal dependence measurements on 4H-SiC Schottky diode

Semiconductors - In this paper the effects of high energy (3.0 MeV) electrons irradiation over a dose ranges from 6 to 15 MGy at elevated temperatures 298 to 448 K on the current-voltage...     

Localized electron irradiation methods and their application to detection of flow-field of point defects

We propose new techniques of electron irradiation for studying the kinetics of simple point defects and their agglomeration, by making the most use of the intrinsic function of an ultrahigh-voltage scanning transmission electron microscope. The methods enable us to realize a very high defect production rate at a localized area and create a spot or band-shape source of point defects. The present methods were applied to an attempt to detect the point defects flowing out of a very localized area, examining the growth and shrinkage of pre-introduced interstitial clusters. At low temperatures where vacancies are immobile, outflow of the interstitials was observed. In contrast, at an elevated temperature where vacancies are mobile, outflow of the vacancies seemed to play a dominant role in the apparent secondary defect reactions. A possible explanation to aid understanding of the present results is proposed.     

Defect formation and recrystallization mechanisms in silicon-on-sapphire films under ion irradiation

The effect of the parameters (energy, dose) of the irradiation of silicon-on-sapphire (SOS) structures with ions Si⁺ ions on the quality of the silicon-film crystal structure after solid-phase epitaxial recrystallization and annealing is studied. It is shown that the most efficient mechanism of crystal-structure recovery is recrystallization from the silicon surface layer which is a seed.     

Effect of electron and proton irradiation on characteristics of SiC surface-barrier detectors of nuclear radiation

Structures with a Schottky barrier based on CVD-grown 4H-SiC films were irradiated with 8 MeV protons and 900 keV electrons. The maximum fluences were 10¹⁴ and 3 × 10¹⁶ cm^?2, respectively. It was found that, in the case of electrons, the primarily introduced radiation defects are closely spaced Frenkel pairs. Changes in the electrical characteristics of the structures were compared. Capacitance methods and nuclear spectrometry were employed. The latter technique was used to determine the charge collection efficiency under pulsed ionization with α-particles. It was determined that, under proton irradiation, the charge collection efficiency steadily decreases as the fluence increases. For electrons, the efficiency remains unchanged in the fluence range (1–3) × 10¹⁶ cm^?2. However, a fluence of 3 × 10¹⁶ cm^?2 leads to a pronounced increase in the non-uniformity of charge transport conditions throughout the sample volume.     

Comparison of gold, platinum, and electron irradiation for controlling lifetime in power rectifiers

Recombination statistics based upon a single dominant level have been used to predict the relative characteristics of gold-diffused, platinum-diffused, and electron-irradiated silicon power rectifiers and thyristors. These calculations indicate that gold-diffused devices will have the best trade-off curve between forward voltage drop and reverse recovery time, while exhibiting the highest leakage currents. Electron-irradiated devices are predicted to have the worst trade-off curve among the three cases and twice the leakage current of platinum-diffused devices. The leakage current of platinum-diffused devices is shown to be an order of magnitude lower than gold-diffused devices. The measured characteristics of gold-diffused, platinum-diffused, and electron-irradiated power rectifiers are shown to be in good agreement with these calculations. The results are also shown to be applicable to power thyristors.