SiC功率MOSFET损耗特性的研究

发布时间：2018-02-02 18:24

本文关键词： SiC功率MOSFET 开关损耗界面态输出电容　出处：《安徽工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着当今科技的日渐发展,碳化硅功率器件备受人们的关注。以SiC功率MOSFET为例,其低导通电阻、耐高温和高开关频率等特性使之深受高电压大功率开关设备的青睐。SiC功率MOSFET开关损耗的真实估计对于准确预测功率电子器件的最大结温和效率至关重要,因此,正确的开关损耗计算公式尤为重要。传统测量开关损耗的方法对于像SiC功率MOSFET这样的功率器件缺乏一些物理角度上的理解。本文将从物理角度出发,对传统计算开关损耗的公式提出质疑。通过半导体器件仿真软件ATLAS对SiC功率MOSFET的开关动态进行建模仿真,分析流过SiC功率MOSFET的沟道电流与漏源极电流之间的差异,以及Si C功率MOSFET的输出电容对开关损耗的真实影响,并用实验辅以证明,得到正确的开关损耗计算公式。当今商业化的半导体器件仿真软件中的迁移率模型大多数是基于Si器件的开发,并不能体现SiO2/Si C界面处的陷阱对于沟道中载流子的散射影响。通过引入能正确反映界面陷阱对载流子作用的迁移率模型,利用半导体器件仿真软件研究了界面陷阱对SiC功率MOSFET动态特性的影响。位于Si O2/SiC界面处密度较高的陷阱,不仅俘获SiC功率MOSFET沟道中的载流子,而且对沟道中的载流子形成散射、降低载流子的迁移率,因而严重影响了SiC功率MOSFET的开关特性。研究结果表明,随着界面陷阱密度的增加,Si C功率MOSFET开通过程变慢,开通损耗随之增加,而关断过程加快,关断损耗随之减小;但是由于沟道载流子数量的减少、导通电阻的增加,总损耗是随着界面陷阱密度的增加而增加。通过ATLAS的仿真结果与实验验证,证明了传统开关损耗计算公式的不准确之处。此外,采用ATLAS建立4H-SiC MOSFET模型,通过改变模型中的界面陷阱密度,定量研究界面陷阱对SiC器件特性的影响。对今后SiC功率MOSFET的研究和发展起到了一定的作用。
[Abstract]:With the development of science and technology, silicon carbide power devices have attracted much attention. Taking SiC power MOSFET as an example, its low on-resistance. The characteristics of high temperature resistance and high switching frequency make it favored by high voltage and high power switchgear. The true estimation of sic power MOSFET switching loss can accurately predict the maximum junction temperature efficiency of power electronic devices. Vital. So... The correct formula for calculating switching loss is particularly important. The traditional method of measuring switching loss lacks some physical understanding of power devices such as SiC power MOSFET. Fat. The traditional formula for calculating switching loss is questioned. The switching dynamics of SiC power MOSFET is modeled and simulated by the semiconductor device simulation software ATLAS. The difference between channel current and drain current of SiC power MOSFET and the real effect of output capacitance of SiC power MOSFET on switching loss are analyzed. With the help of experiments, the correct formula of switching loss is obtained. Most of the mobility models in the commercial simulation software of semiconductor devices are based on the development of Si devices. It can not reflect the effect of trapping at SiO2/Si C interface on carrier scattering in channel. By introducing a mobility model which can correctly reflect the interaction of interface trap with carrier. The influence of interface traps on the dynamic characteristics of SiC power MOSFET is studied by using semiconductor device simulation software. Not only the carrier in the SiC power MOSFET channel is captured, but also the carrier in the channel is scattered, which reduces the mobility of the carrier. As a result, the switching characteristics of SiC power MOSFET are seriously affected. The results show that the switching process of sic power MOSFET becomes slower with the increase of interface trap density. The turn-on loss increases and the turn-off process accelerates and the turn-off loss decreases. However, due to the decrease of the number of channel carriers and the increase of on-resistance, the total loss increases with the increase of interface trap density. The inaccuracy of the traditional formula for calculating the switching loss is proved. In addition, the 4H-SiC MOSFET model is established by ATLAS, and the interface trap density is changed by changing the interface trap density in the model. The effects of interface traps on the characteristics of SiC devices are quantitatively studied, which will play an important role in the research and development of SiC power MOSFET in the future.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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