A study on the electric properties of single-junction GaAs solar cells under the combined radiation of low-energy protons and electrons

Displacement damage induced by charged particle radiation is the main cause of degradation of orbital-service solar cells, while the radiation-induced ionization shows no permanent damage effect on their electrical properties. It is reported that in single crystal silicon solar cells, low-energy electron radiation does not exert permanent degradation of their properties, but the fluence of electron radiation exerts an influence on the damage magnitude under the combined radiation of protons and electrons. The electrical properties of the single-junction GaAs/Ge solar cells were investigated after irradiation by sequential and synchronous electron and proton beams. Low-energy electron radiation showed no effects on the change of the solar cell properties during sequential or synchronous irradiation, implying ionization during particle radiation could not exert influence on the displacement damage process to the solar cells under the experimental conditions.     

Equivalence of Radiation Particles for Permanent Damage in Semiconductor Devices

Selected transistors and diodes have been irradiated by various types and energies of dislocating radiation. Irradiation by protons of 10-Mev, neutrons of a reactor spectrum, electrons of 5, 10, and 25-Mev, gamma rays from cobalt-60, and bremsstrahlung from stopping of 5-Mev electrons are discussed. Passive and dynamic monitoring of permanent radiation damage was performed for exposures ranging from "threshold" to failure doses, utilizing various exposure rates. Changes in transistor forward current gain and changes in diode lifetime are presented in terms of integrated "particle" flux. From such analysis, the feasibility of ascribing an equivalence of radiation particles for aermanent damage in transistors and diodes has been successfully shown. Comparative damage curves, correlations of operational degradation with defect densities, and preliminary equivalences are presented.     

Electron Damage Coefficients in P-Type Silicon

Crucible grown p-type silicon, as used for the base of many commercial solar cells, exhibits a damage coefficient under electron bombardment that appears to involve a double defect in each recombination center. The damage coefficient has been fitted to an empirical formula that accounts for silicon resistivity and for energy of the bombarding particles. To apply this formulation to a practical evaluation of solar cell damage in orbit, two complications were considered. The first is the angular distribution of the space radiation incident on the cell. An experiment showed that electron flux, and not current, determines the extent of the damage. The second is the presence of a transparent coverslide over the cell. By the application of Monte Carlo data for the transmission loss and energy degradation of the electrons, modifications to the damage coefficient can be made to account for coverslide shielding. An exponential attenuation appears adequate to describe these shielding effects. The end product of this study is an analytic formula for the damage coefficient that allows a simple calculation of the damage caused by energetic electrons to n/p silicon solar cells with coverslides.     

柔性倒置赝型三结太阳电池高能质子辐射效应研究

为考察柔性薄膜GaInP/GaAs/InGaAs倒赝型三结（IMM3J）太阳电池的抗辐照性能,本文对其进行了1、3、5 MeV高能质子辐照。SRIM模拟结果表明,1、3、5 MeV质子辐照在IMM3J电池中造成均匀的位移损伤。光特性(LIV)结果表明,开路电压(Voc)、短路电流(Isc)和最大输出功率(Pmax)与质子注量呈对数退化规律。通过非电离能量损失（NIEL）将不同能量质子的注量转化为位移损伤剂量（DDD）,结果显示,Voc和Pmax与DDD呈对数退化规律,而Isc遵循两种不同的退化规律。光谱响应测试证明,GaInP子电池具有优异的抗辐照性能,3个子电池中InGaAs(10 eV)子电池的抗辐照性能最差。     

Passage of radiation through a test hole

This paper discusses the passage of monoenergetic radiation through rectangular, cylindrical, and ring-shaped test holes. It is assumed that the sources are located at the far end and on the lateral surface of the test hole. Formulas are derived for calculating the radiation flux in test holes passing through both the shield and the core of the reactor. The results of the theory are compared with experiment.     

Radiation Studies on GaAs and Si Devices

GaAs and Si n/p cells were irradiated with 100 kev and 17.6 Mev protons, and 0.8 and 5.6 Mev electrons. The resulting difference in performance is interpreted in terms of the initial lifetime and the photo-absorption process. It is concluded that GaAs cells can deliver a given power longer than Si cells in a radiation field of high-energy protons and electrons. Thin shields will be required for both cells in environments of low-energy protons. It is suggested that the recombination centers introduced in silicon by high-energy particles are more effective than those introduced by 0.8 Mev electrons.     

Proton-Neutron Damage Equivalence in Si and Ge Semiconductors

Following an analysis of the basic radiation damage processes in semiconductors, and an analysis of existing radiation effects data, a proton-neutron damage equivalence was experimentally determined for silicon solar cells. The basis for comparison is the degradation of minority carrier lifetime during irradiation, as expressed by the lifetime damage constant, K?, or the diffusion length damage constant, KL . Both p on n cells and n on p cells were irradiated with 96, 69, 48 Mev protons, and with fission and moderated neutrons. Measurements were made on the degradation of the solar cell dark voltage-current characteristics, the forward bias characteristics under one sun illumination, and the short circuit current response to monochromatic illumination of one micron wavelength. The degradation of minority carrier diffusion length was calculated from the short circuit current response at one micron. From the analysis of radiation damage processes in silicon, the derivation of a theoretical proton-neutron damage equivalence was hindered by inadequately developed theory relating the number and type of active defects associated with the vacancies created by the incident particles. The analysis of available data indicate that a reliable proton-neuton damage equivalence in Si or Ge is not possible, due to the spread in the existing damage constants and the absence of damage constants for proton and neutron irradiations of equivalent samples. The experimentally determined proton to neutron ratio of minority carrier diffusion length damage constants in silicon solar cells ranges from 0.96 to 4.     

Lithium-Doped Radiation-Resistant Silicon Solar Cells

Photovoltaic measurements indicate that lithium in the n-type region of floating-zone silicon p-on-n solar cells interacts with radiation damage induced by 1 MeV electrons or 16.8MeV protons. The centers formed by this interaction do not degrade the minority-carrier lifetime; therefore, these cells are potentially the most radiation-resistant ones available. The interaction involves the motion of lithium; thus, the cell temperature and the radiation rate are important in establishing the amount of degradation which is observed. At room temperature and low rates, the cell output does not degrade. At room temperature and high rates, the cell output degrades but it recovers after irradiation, i.e. the cells are self-healing. The rate which can be used without causing observable decay in the photovoltaic output increases with the cell temperature.     

Shielding Problems for Manned Space Missions

In order to estimate the magnitude of the radiation hazard presented by solar flare and Van Allen belt proton radiation, a simple spherical-shell shield geometry was chosen and physical dose calculatved as a function of shell thickness. Both point-target and body-phantom definitions of dose were used to define the primary particle dose. The secondary particles formed in the shield are shown to contributve a significant fraction of the total dose in the case of the 10 May 1959 flare spectrum and an aluminum shield.     

An Analysis of Non-Uniform Proton Irradiation Damage in Silicon Solar Cells

Experimental data obtained on the degradation of the short-circuit current in 1-ohm-cm N/P silicon solar cells irradiated by low-energy, 0.1-3.0 MeV, protons were analyzed with the aid of an N-layer solar-cell model. The results show that the damage constant, K(Ep), rises less rapidly with decreasing proton energy, Ep, than it does at higher proton energies. The derived damage law can be analytically described as follows: K(Ep) = Ep ? E1 =.962 MeV E1 ? Ep =2.98 MeV where K0 = 1.92 × 10-5 p-1 C1 = 1.08 MeV-1 C2 = 0.85 This representation has been found adequate for incident proton energies of 0.5, 1, and 3 MeV and definitive for Ep ? 0.1 MeV. The value of Ko listed should be considered as representative only of the particular solar cells analyzed.     

Low Energy Proton Damage to Solar Cells

Various types of silicon solar cells have been irradiated with 4.6 - 4.8 Mev protons in two separate experiments. In the first experiment, variations included the bulk material, impurity concentration, and oxygen concentration; the second experiment involved the cells of various manufacturers. Changes in diffusion length, spectral response, and efficiency under sun-like illumination are presented. Annealing effects in terms of the aforermentioned parameters are given. Comparison of the effects of this damage to that of 1 Mev electrons is made. Some preliminary results on the effects of proton damage to GaAs photovoltaic cells are also mentioned.     

Radiation Effects on Multiplier Phototubes

A multiplier phototube is an extremely sensitive device used to measure ultraviolet, visible and near infrared radiant energy. Physically, multiplier phototubes are high vacuum tubes which are comprised of a photo-cathode; an electron lens, which directs the photo-electrons onto the first dynode; a series of dynodes or amplifying stages; and an anode or collector. The use of multiplier phototubes in photometric and nuclear detectors for satellite systems has increased dramatically within the last few years. Because many of these systems are subjected to either natural or artificially created radiation, such as encountered in the Van Allen belts, or the South Atlantic anomaly, or galactic or solar cosmic radiation, a study of the behavior of these tubes under such conditions has become necessary. This paper summarizes the work of EMR and that of many other investigators, and discusses degradation of optical windows used; effects on photocathodes and dynodes; effects on noise, dark current and resolution. A list of conclusions is given.     

Mechanisms of Radiation Effects on Lasers

Lasers offer many potential advantages for space communications and space instrumentation. Their performance is, however, affected by the high energy radiation found in the space environment, e.g., trapped proton and electrons, solar flare protons, and possibly gamma rays and neutrons from on-board nuclear power, auxiliary or propulsive. We report here on some studies of the effects observed on lasers and laser components exposed to irradiation, and in particular on the mechanisms of these effects.     

CMOS运算放大器在不同辐射环境下的辐照响应

介绍了ＬＦ７６５０ ＣＭＯＳ运算放大器在＾６０Ｃｏγ射线,１ＭｅＶ电子了４,７,３０ＭｅＶ不同能量质子辐照环境中的响应规律及＾６０Ｃｏγ射线和１ＭｅＶ电子辐照损伤在室温和１００℃高温条件下的退火特性,探讨了引起ＣＭＯＳ运放在不同辐射环境中辐照响应出现差异的损伤机理,并对ＣＭＯＳ运放电路在不同辐射环境中表现出的与ＣＭＯＳ数字电路不同的响应特征给予了解释。     

Synchrotron radiation intensity for 50-MeV to 50-GeV electrons

Tables for practical calculations of the intensity of synchrotron radiation are presented for 50-MeV to 50-GeV electrons. The tables, accurate to five significant figures, list the angular distribution of the intensity and the flux of radiation passing through a rectangular aperture. Two extended versions are given in a form suitable for scaling to any electron energy.     

Synchrotron radiation intensity for 50-MeV to 50-GeV electrons

Tables for practical calculations of the intensity of synchrotron radiation are presented for 50-MeV to 50-GeV electrons. The tables, accurate to five significant figures, list the angular distribution of the intensity and the flux of radiation passing through a rectangular aperture. Two extended versions are given in a form suitable for scaling to any electron energy.     

The Role of Atomic Collisions in Space Phenomena

Collisions involving electrons, photons, and atomic systems are important in upper atmospheric and astrophysical phenomena and in the exploration of space. Some of these types of reactions are enumerated and described. Examples are given of their significance with respect to diffusion in the atmosphere; radio communications and radar tracking; the excitation and study of the airglow and aurorae; the Van Allen radiation belts; estimation of densities, composition, and temperatures of nebulae and stellar atmospheres; the mapping of hydrogen in interstellar space; and the erosion of space vehicles and planets. Some of the work at the Georgia Institute of Technology on ion mobilities, ion-molecule reactions, ionization, and charge transfer is described.     

双极运算放大器的质子辐照效应

研究了ＯＰ－７双极运算放大器在８ＭｅＶ，１２ＭｅＶ两种能量下的质子辐照效应及损伤特性，并通过对电路内部的损伤分析，探讨了各敏感参数和的变化规律，结果表明，由位移损伤和电离辐射损伤引起的晶体管增益衰降是导致运算放大器各参数变化的主要原因。     

A study on the degradation of GaAs/Ge solar cells irradiated by <200 keV protons

Damage effects in GaAs/Ge solar cells irradiated by <200 keV protons were studied by measuring their electrical properties and spectral response together with SRIM simulations. Proton energies of 40, 70 and 170 keV were chosen. Experimental results show that the short circuit current, open circuit voltage and maximum power decrease with increasing proton fluence. The degradation of the open circuit voltage is highest for 70 keV irradiation and lowest for 40 keV irradiation. The degradation of short circuit current decreases with increasing proton energy. According to SRIM simulations and spectral response analysis, the above changes in electrical properties are mainly related to damage in different regions of the solar cells.     

单能电子诱发DNA损伤的理论计算

利用径迹结构的方法模拟了单能电子从入射DNA水溶液到最终产生DNA损伤的早期物理和化学变化过程。着重研究了直接能量沉积导致碱基损伤的判断方法、DNA损伤穷举分类的定义及计算机实现方法,以及确定自由基产生位置的随机抽样方法。结果表明：物理、化学径迹与DNA的反应主要以NB（nobreak）的形式存在,而在链断裂中,主要也以易修复的单链断裂(SSB)为主;在为数不多的双链断裂（DSB）中,复杂DSB占到相当数量的份额。验证了DNA是辐射作用主要“靶”的假定。