Formation of carbon interstitial-related defect levels by thermal injection of carbon into $n$-type 4$H$-SiC

Abstract

Electrical properties of point defects in 4$H$-SiC have been studied extensively, but those related to carbon interstitials (C${}_i$) have remained surprisingly elusive until now. Indeed, when introduced via ion irradiation or implantation, signatures related to C${}_i$ observed by deep level transient spectroscopy (DLTS) tend to overlap with those of other primary defects, making the direct identification of C${}_i$-related levels difficult. Recent literature has suggested to assign the so-called M center, often found in as-irradiated 4H-SiC, to charge state transitions of the C${}_i$ defect in different configurations. In this work, we have introduced excess carbon into low-doped n-type 150 μm thick 4$H$-SiC epilayers by thermal annealing, with a pyrolyzed carbon cap on the sample surface acting as a carbon source. Because the layers exhibited initially low concentrations of carbon vacancies ([V${}_C$] = 10${}^{11}$ cm${}^{-3}$), this enabled us to study the case of complete V${}_C$ annihilation, and formation of defects due to excess carbon, i.e. carbon interstitials C${}_i$ and their higher-order complexes. We report on the occurrence of several new levels upon C injection which are likely C${}_i$-related. Their properties are different from those found for the M center, which points towards a different structural identity of the detected levels. This suggests the existence of a rich variety of C${}_i$-related defects. The study will also help generating new insights into the microscopic process of V${}_C$ annihilation during carbon injection processes.

References in corpus (6)

• Coherent control of single spins in silicon carbide at room temperature
• Isolated electron spins in silicon carbide with millisecond-coherence times
• Ab initio study of the migration of intrinsic defects in 3C-SiC
• Native point defects and carbon clusters in 4H-SiC: A hybrid functional study
• Conversion pathways of primary defects by annealing in proton-irradiated n-type 4H-SiC
• The M-center in 4H-SiC is a carbon self-interstitial

Cited by in corpus (1)

• Distinguishing the EH1 and S1 defects in n-type 4H-SiC by Laplace DLTS