【作者】 赵慧杰；

【导师】 何世禹； 黄才勇；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2008， 博士

【摘要】 本文通过空间辐射环境地面模拟试验,对航天器应用的GaAs/Ge太阳电池在质子、电子及其综合辐照作用下电性能的演化规律及损伤机理进行了研究。采用了单因素质子、单因素电子、先质子后电子、先电子后质子以及质子和电子同时辐照五种辐照方式。质子与电子的能量选为50～170keV,电子注量达到1×10¹⁶e/cm²,质子照注量达到3×10¹²p/cm²。通过伏安特性、光谱响应、光致发光光谱、深能级瞬态谱、光学反射光谱及霍尔效应等测试手段揭示了质子、电子单因素和综合因素辐照条件下GaAs/Ge太阳电池的性能演化规律,分析了辐照导致GaAs/Ge太阳电池短路电流（Isc）、开路电压（Voc）、最大功率（Pm）和填充因子（FF）等特性参数退化的机理。质子辐照后I-V测试分析结果表明,小于200keV质子辐照能量相同时,随辐照注量的增加,GaAs/Ge太阳电池的Isc、Voc、Pm和FF等特性参数降低。辐照注量相同时,质子能量越高,电池性能衰降程度越大。质子辐照后GaAs/Ge太阳电池的量子效率随辐照能量和注量增大而降低;能量较低时呈现短波效应,而随着能量增高,引起短波效应的同时出现长波效应。随着辐照能量和注量的增加,GaAs/Ge太阳电池光致发光峰的峰高降低,半峰宽变宽,峰位右移。质子辐照在GaAs/Ge太阳电池的p区、结区和n区分别引入了高密度的深能级缺陷,缺陷的能级位置随辐照能量和注量的不同而变化。在所试验的GaAs/Ge太阳电池中主要产生了Ec-0.24eV、Ec-0.33eV、Ec-0.38eV、Ec-0.52eV、Ec-0.72eV和Ec-0.75eV六个深能级。原位I-V测试分析结果表明,小于200keV的电子辐照能使GaAs/Ge太阳电池的性能参数降低。电子辐照能量相同时,电池的Isc、Voc、Pm和FF等性能参数均随辐照注量的增加而降低。辐照注量相同时,电池性能随辐照能量增高而下降。能量小于200keV的电子辐照对GaAs/Ge太阳电池引起的性能衰降,可以在室温放置过程中逐步得到恢复。不同能量与注量低能电子辐照后,GaAs/Ge太阳电池的量子效率有所减小,光学反射率有所升高,但尚未发现深能级缺陷形成。低能质子与电子顺序辐照和同时辐照试验结果表明,同时辐照比顺序辐照更能使GaAs/Ge太阳电池的电性能降低。顺序辐照时,低能质子对电池性能退化起主要作用。质子与电子同时辐照时,GaAs/Ge太阳电池量子效率衰降最严重,其次是电子和质子的顺序辐照。质子与电子综合辐照对GaAs/Ge太阳电池性能的影响具有协合效应。GaAs/Ge太阳电池综合辐照前后PL光谱发生变化,GaAs特征峰强度经综合辐照后明显降低,半峰宽有少许增宽,峰位发生轻微红移。综合辐照下,量子效率下降的幅度依次是:质子与电子同时辐照>质子和电子顺序辐照>单独质子辐照>>单独电子辐照。更多还原

【Abstract】 Using the ground-based environmental simulations for the irradiations of protons, electrons and their synergistic effects, the electric property degradations and damage mechanisms of the new-generation GaAs/Ge solar cells were investigated. In this paper, there were five types of irradiated modes chosen to perform the investigations, namely irradiations of single protons, single electrons, protons or electrons followed sequentially by electrons or protons, and synchronous one of both electrons and protons. The energies of protons and electrons were set in the range from 70keV to 170keV, while the maximum fluences were up to 1×1016cm-2 for electrons and 3×1012cm-2 for protons. Some complementary techniques, such as I-V measurements, spectral responses (SR) analysis, photoluminescence spectra (PL), deep level transition spectra (DLTS), x-ray double-crystal diffraction and Hall effect analysis, were applied to expose the property evolutions and damaged mechanisms of the irradiated cells.The results indicate that, after <200keV proton irradiations, the electric properties such as the short circuit current (Isc),the open circuit voltage (Voc) ,the maximum output power (Pm) and the filling factor (FF) of the GaAs/Ge solar cells decrease with increasing proton fluence. In the meantime, the damage extent of the solar cells increases with increasing proton energy at a given flux and fluence of protons.The analysis of various types of spectra present that proton irradiation induces a great damage and degrades the conversion efficiency of the solar cells. The degradation extent of the spectral responses of the GaAs/Ge solar cells increases with proton energy and fluence in their ranges under investigation. Under the proton irradiation, the degradation occurs in the short wavelength band as the proton energy is lower while the spectral response decreases tend to take place in the longer wavelength bands with increasing the proton energy. The experimental results show also that with increasing the proton energy and fluence, the photoluminescence peak (at around 890 nm) of the GaAs/Ge solar cells reduces, broadens intensively and also presents a slight red-shift in the mean time. It is found from the DLTS results that proton irradiations induce various kinds of deep-level defects in the solar cells. The concentrations and the types of deep level defects in the solar cell change with the proton energy and fluence. The detected defects show deep-level energies at Ec-0.25eV, Ec-0.35eV, Ec-0.54eV, Ec-0.72eV, and Ec-0.75eV, respectively.During the <200keV electron irradiation, the in-situ I-V measurements indicate that the irradiation could reduce the electric parameters of the solar cells. The degradation extent increases with increasing the electron energies and fluences. However, it is interested to be noted that this property degradation induced by <200keV electrons can be recovered gradually during afterwards storage period at room temperature. It was also found that the external quantum efficiency shows a slight decrease but the reflectance of the solar cells rises slightly after the electron irradiations. No deep-level defects were detected in the eellctron-irradiated solar cells.The results on the combined irradiations of electrons and protons indicate that the electric properties of the solar cells present more degradation after irradiations in the order of the synchronous proton/electrons irradiation, the sequential electron irradiation followed by protons and then protons irradiation followed by electrons. During the sequential process, the damage induced by low-energy protons domains the property degradation of the solar cells. These results imply that there is a synergistic damage effect during the synchronous irradiations. It was also found the degradation effects on the PL spectra and spectral responses of the combined irradiations of the solar cells. Under the experimented irradiations, the quantum effeciencies decrease and the decrease extent is in the following order: synchronous irradiation of electrons and protons > sequential irradiations of protons (electrons) followed by electrons (protons) > single proton irradiations >> single electron irradiations.更多还原