Single Color Centers in Silicon Carbide: electro-optical access via epitaxial graphene

• Applicant: Professor Dr. Heiko B. Weber
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 337455822

The physics of color centers in wide bandgap semiconductors has attracted substantial attention as it provides access to fundamental quantum phenomena. Compared to the prototypic NV center in diamond, color centers in silicon carbide (SiC) exhibit similar properties with the additional benefit of a fully mature technology for SiC device fabrication. The proposal targets the simultaneous electrical and optical characterization of color centers, in particular intrinsic defects, in SiC. For their generation we develop a methodology that combines ion implantation and optimized annealing such that smallest defect concentrations underneath the SiC (0001) surface can be achieved with the ultimate goal of access to single defects. The (0001) surface will be equipped with epitaxially grown graphene electrodes, such that a space charge region results, in which the defect under investigation can be electrostatically controlled. In particular, one can fill or empty the defect with charge at will. In connection with our patented epitaxial monolithic SiC/Graphene transistors, we will further optimize the Drain-Current Deep-Level Transient Spectroscopy with the goal of single-defect sensitivity in the electrical signal. Simultaneously, the transparent graphene electrodes allow optical access to the very same defect, on which we will perform spectroscopy in the visible and infrared spectral range using a confocal microscope. We expect via the combined electrical and optical control as well as the electrical and optical characterization at the very same color center a deep understanding of the excitation spectra and, thus, build a bridge between electrical and optical excitation. This refined methodology of defect analysis has significant importance for SiC electronic device developments. It further offers an opportunity to build single-photon sources with electrical control in this powerful and mature material system, which paves the way, for example, for highly sensitive sensors.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Michael Krieger