碳化硅结势垒肖特基二极管的质子辐射效应

Proton Radiation Effect of Silicon Carbide Junction Barrier Schottky Diode

碳化硅结势垒肖特基二极管(SiC JBS)是新一代航天器电推进系统的关键部件,但高能粒子辐射严重威胁其可靠性与稳定性。为揭示其辐射损伤机理,为其抗辐射加固设计与考核评估储备数据,本研究基于加速器开展了先进商用SiC JBS 10~20 MeV中能质子地面辐照实验,并提取器件辐照前后的正向伏安特性、反向伏安特性、电容电压等电学参数及缺陷特性。系统分析器件关键特性随辐照条件的改变规律。结果显示,质子辐照引起了器件肖特基势垒升高、载流子浓度降低,且10 MeV较低能质子导致的位移损伤退化更严重。分析认为,PN结界面缺陷导致高性能商用SiC JBS反向电学性能对中能质子的辐照更加敏感,正向特性相对稳定,辐照生碳缺陷造成载流子去除效应是引起SiC JBS性能退化的主要机制。

Silicon carbide(SiC) junction barrier schottky(JBS) diode is a key component of the new generation spacecraft electric propulsion system, but its reliability and stability are seriously threatened by high-energy particles radiation, especially protons. A large number of protons in space can not only cause displacement damage effect, but also lead to single event effect and total ionizing dose effect. In order to reveal the mechanism of displacement damage effect of SiC JBS by protons and reserve data for its radiation hardening design and assessment, the irradiation experiment of advanced commercial SiC JBS was carried out based on the 10-20 MeV medium energy protons from the HI-13 Tandem Accelerator. And based on the equivalent displacement damage dose calculation method, the fluence of protons induced displacement damage used in the proton irradiation experiment can be equivalent to the degree of displacement damage by protons accumulated in the typical spacecraft orbit for 10 years. The electrical properties such as forward volt ampere characteristics(I-V), reverse I-V, capacitive voltage(C-V) and radiation induced defects were extracted and analyzed before and after irradiation. The change rule of the key characteristics of the device with the irradiation conditions is systematically analyzed. It is proved that proton irradiation will increase the Schottky barrier and reduce the carrier concentration of the device, and the displacement damage degradation of the device caused by 10 MeV is more serious. The analysis shows that the reverse electrical properties of commercial SiC JBS of high performance are more sensitive to intermediate energy protons due to the effect of PN junction interface defect. However, medium energy proton irradiation will not cause complete damage to the Schottky barrier of the device, so its forward characteristics have not been greatly degraded after proton irradiation. And the carrier removal effect caused by carbon defects induced by the protons’ irradiation are the main mechanism causing the bad properties of SiC JBS. This paper can provide important research data for the assessment and evaluation of the resistance to medium energy proton displacement damage of advanced SiC JBS and the development of its radiation hardening technology.