On the interpretation of confocal spectral depth profiling of color center and carrier concentration by photoluminescence and Raman of implanted 4H–SiC

Abstract

Point defects in silicon carbide (SiC) formed after ion implantation can serve as color centers for quantum sensing, or as donors or acceptors to provide carriers to influence electrical performance. Confocal spectroscopic characterization allows the determination of point defect-related optical and electrical properties without sample preparation or destruction. However, phenomena such as refraction and aberration can complicate the interpretation of the results of three-dimensional spectroscopy. Here, we used H+, N+ and He+ implantation to fabricate silicon vacancy (VSi) color centers in SiC and used confocal spectroscopy to characterize bulk and thin layer of VSi contained materials. 270 keV H+ is more advantageous than 150 keV N+ in preparing VSi due to the preservation of better lattice integrity. For thin-layer VSi samples, the photoluminescence intensity maxima of VSi were distributed at 2–6.5 μm above the surface. To explain such confusing phenomenon in depth profiles focusing on and above the surface the effective excitation volume and chromatic aberration are discussed and proposed for explanation of the results. Furthermore, the ion-implanted layer exhibits a non-negligible effect on the underlying signal during confocal spectral depth profiling, which is attributed to the refraction-related focus degradation.