Study of trapping phenomenon in 4H-SiC MESFETs: dependence on substrate purity
Study of trapping phenomenon in 4H-SiC MESFETs: dependence on substrate purity
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DOI：
10.1109/ted.2002.808559
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发表时间：
2003-04
影响因子：
3.1
通讯作者：
N. Sghaier;J. Bluet;A. Souifi;G. Guillot;E. Morvan;C. Brylinski
中科院分区：
文献类型：
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作者：
N. Sghaier;J. Bluet;A. Souifi;G. Guillot;E. Morvan;C. Brylinski
这项工作表明，“纯度”，意味着在半绝缘（SI）SiC衬底中的电子陷阱的低密度，可以是至关重要的4 H-SiC MESFETs的电气特性。在两种类型的SI衬底上实现的结构进行了研究。第一类是采用物理气相传输（PVT）升华技术生长的钒掺杂衬底。第二类是用高温CVD（HTCVD）技术生长的极低钒含量硅衬底。对于所有的晶体管，I/sub d/-V/sub ds/测量已作为温度的函数进行。在PVT衬底的情况下，已经观察到不同的寄生效应对静态输出特性的影响。频率色散测量的晶体管和漏源输出电导，已实现。结果给出了明确的证据，深陷阱的存在下实现的晶体管上的PVT衬底。这些陷阱的激活能为1.05 eV，俘获截面在10/sup-18/ cm/sup-2/和10/sup-19/ cm/sup-2/之间。它们很可能与钒有关。这些陷阱的存在和寄生效应的输出特性之间的相关性进行了讨论，并建立了陷阱的本地化结构。在HTCVD非常低的钒衬底的情况下，没有寄生效应已被观察到，陷阱的存在下，没有检测到的不同的表征技术。
This work demonstrates that the "purity", meaning the low density of electron traps in a semi-insulating (SI) SiC substrate, can be crucial for the electrical characteristics of 4H-SiC MESFETs. Structures realized on two types of SI substrates have been investigated. The first kind is vanadium doped substrates grown by the classical Physical Vapor Transport (PVT) sublimation technique. The second kind are extremely low vanadium content SI substrates grown by the high temperature CVD (HTCVD) technique. For all the transistors, I/sub d/-V/sub ds/ measurements have been performed as a function of temperature. Different parasitic effects have been observed on the static output characteristics in the case of PVT substrates. Frequency dispersion measurements of the transconductance and drain-source output conductance, have next been realized. The results give clear evidence of the presence of deep traps in the transistors realized on PVT substrates. Those traps have an activation energy of 1.05 eV and a capture cross section between 10/sup -18/ cm/sup -2/ and 10/sup -19/ cm/sup -2/. They are most probably related to vanadium. The correlation between the presence of these traps and the parasitic effects on the output characteristics is discussed and the trap localization in the structure is established. In the case of HTCVD very low vanadium substrates, no parasitic effect have been observed and the presence of traps was not detected by the different characterization techniques.