Electrical Characterization of Defects Introduced in 4H-SiC During High Energy Proton Irradiation and Their Annealing Be
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Electrical characterization of defects introduced in 4H-SiC during high energy proton irradiation and their annealing behavior M. Ahoujja,1 H. C. Crocket,2 M. B. Scott, 2 Y.K. Yeo,2 and R. L. Hengehold2 1 2
Department of Physics, University of Dayton, Dayton, OH, USA Air Force Institute of Technology, Wright-Patterson AFB, OH, USA
ABSTRACT We report on the electrical properties of defects introduced in epitaxial 4H-SiC by 2 MeV protons using deep level transient spectroscopy (DLTS). After proton irradiation with a dose of about 1.5x1014 cm-2, the DLTS measurements were made, and the rate window shows a single broad peak between 280 and 310 K. The intensity of this peak remains unchanged after a thermal anneal at 900 oC for 20 min. However, after annealing at or above 1100 oC, the peak intensity gradually decreases with anneal temperature up to 1500 oC, indicating a decrease in the defect concentration. Because a complete damage recovery of the SiC is not observed even after annealing at 1500 oC, we believe a higher temperature annealing is necessary for a complete recovery. Using a curve fit analysis, a set of deep levels of defect centers were found with energy ranging between 567 and 732 meV. These traps do not exhibit a significant change in the trap energy or capture cross-section parameters as a function of anneal temperature, but the decrease in the trap density with increasing anneal temperature demonstrates a damage recovery. INTRODUCTION SiC’s wide bandgap, high electron saturation velocity, and other superior electrical and thermal properties make it a potential candidate for high power electronic devices that can operate in high temperature and caustic environments.[1] Due to its radiation hardness, 4H-SiC is considered as one of the leading wide band gap materials for space applications. Two types of penetrating radiation in space are high energetic electrons and protons. These high energy particles give rise to a wide range of deep level defect centers such as vacancies and interstitials [2] which ultimately are responsible for degrading satellites on-board electronic components and inducing background noise in detectors and errors in digital circuits.[3] Therefore, a clearer understanding of how SiC films and SiC-based devices behave under a radiation environment is required before SiC devices are incorporated in space applications. In this paper, we report on the electrical characterization of proton irradiated 4H-SiC using deep level transient spectroscopy (DLTS). EXPERIMENT The samples investigated in this study are (0001) n-type (nitrogen) epitaxial 4HSiC grown on n-type (1017 cm-3) SiC substrate using chemical vapor deposition (CVD). The thickness of the epi layer is 5 mm and the concentration of the uncompensated donors
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