Analytical model for reduction of deep levels in SiC by thermal oxidation
Analytical model for reduction of deep levels in SiC by thermal oxidation
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DOI：
10.1063/1.3692766
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发表时间：
2012-03-01
影响因子：
3.2
通讯作者：
Kimoto, Tsunenobu
中科院分区：
文献类型：
--
作者：
Kawahara, Koutarou;Suda, Jun;Kimoto, Tsunenobu
发现了热氧化和C+注入后Ar退火两种捕集阱还原工艺，是降低n型4H-SiC的寿命杀手Z（1/2）中心（E-C - 0.67 eV）的有效方法。研究表明，在Z（1/2）中心减小的同时，圈闭-还原过程产生了新的深层。对两种捕集阱还原过程缺陷行为（还原、生成和深度剖面变化）的比较表明，热氧化引起的深度水平降低可以用间隙扩散模型来解释。根据扩散方程对氧化后缺陷的分布进行了数值计算，其中SiO2/SiC界面处产生的间隙扩散到SiC体上，占据了与Z（1/2）中心原点相关的空位。基于所提出的分析模型的预测对氧化后的SiC在任何温度、任何氧化时间和任何初始Z(1/2)-浓度下都是有效的。实验结果的基础上,作者实现了消除Z(1/2)中心的深度约90μm在样本相对较高initial-Z(1/2)浓度的10(13)厘米(3)由热氧化在1400摄氏度为16.5 h。此外,载体寿命预测的SiC Z(1/2)配置文件实现了通过计算基于扩散方程,认为excited-carrier扩散和复合外延层,底物,在表面。(C) 2012年美国物理研究所。[http://dx.doi.org/10.1063/1.3692766]
Two trap-reduction processes, thermal oxidation and C+ implantation followed by Ar annealing, have been discovered, being effective ways for reducing the Z(1/2) center (E-C - 0.67 eV), which is a lifetime killer in n-type 4H-SiC. In this study, it is shown that new deep levels are generated by the trap-reduction processes in parallel with the reduction of the Z(1/2) center. A comparison of defect behaviors (reduction, generation, and change of the depth profile) for the two trap-reduction processes shows that the reduction of deep levels by thermal oxidation can be explained by an interstitial diffusion model. Prediction of the defect distributions after oxidation was achieved by a numerical calculation based on a diffusion equation, in which interstitials generated at the SiO2/SiC interface diffuse to the SiC bulk and occupy vacancies related to the origin of the Z(1/2) center. The prediction based on the proposed analytical model is mostly valid for SiC after oxidation at any temperature, for any oxidation time, and any initial Z(1/2)-concentration. Based on the results, the authors experimentally achieved the elimination of the Z(1/2) center to a depth of about 90 mu m in the sample with a relatively high initial-Z(1/2)-concentration of 10(13) cm(-3) by thermal oxidation at 1400 degrees C for 16.5 h. Furthermore, prediction of carrier lifetimes in SiC from the Z(1/2) profiles was realized through calculation based on a diffusion equation, which considers excited-carrier diffusion and recombination in the epilayer, in the substrate, and at the surface. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692766]