Papers by Keyword: Nitrogen Concentration

Abstract: Spin defects of which states can be manipulated in Silicon Carbide (SiC) have drawn considerable attention because of their applications to quantum technologies. The single negatively-charged pairs of V_Si and nitrogen atom (N) on an adjacent C site (N_CV_Si^- center) in SiC is suitable for them. This paper reports the formation of N_CV_Si^- centers on 4H-SiC epilayers with different nitrogen concentrations using light/heavy ion irradiation and subsequent thermal annealing. The formation of N_CV_Si^- centers is characterized by the near infrared photoluminescence (PL) spectroscopy. It is shown that the PL intensity from N_CV_Si^- centers depends on the N concentration and the ion irradiation conditions. The PL intensity increases monotonically with increasing the N concentration when the N concentration is above 2.6×10¹⁶ cm^-3, whereas no linear correlation between them does not appear below that N concentration. Although the PL intensity increases with increasing defects induced by ion irradiation, the PL quenching due to neighboring residual defects appear at above the areal vacancy concentration of 10¹⁷ vac/cm² and the broad Raman scattering spectra originated from vibration modes of amorphized regions hinder the PL from N_CV_Si^- centers at above 10¹⁸ vac/cm². The formation mechanism and the charge state stability of N_CV_Si^- centers are discussed based on the obtained results.

Abstract: We investigated the run-to-run fluctuation in growth conditions of physical vapor transport growth of 4H-SiC boules through observations of surface morphology on the (000-1) facet of the boules. The boules, which were grown under the same macroscopic growth conditions, exhibited slightly different surface morphologies. This indicates that some microscopic growth parameters that influence the surface morphology fluctuate between growth runs. We have considered the C/Si ratio of the vapor sublimed from the source material as a major parameter and discussed the associated variations in the physical and surface properties of the grown crystals.

Abstract: In this work we present a comprehensive comparison of ultra thin thermally nitrided (TN) to plasma nitrided (PN) gate dielectrics (GD). We will show that thermal nitridation is a promising technique to increase the nitrogen concentration up to 25%. Furthermore, we will demonstrate that ultra thin thermally nitrided GD have the potential to be an alternative solution compared to plasma nitrided GD. This work includes the analysis of physical and electrical parameters as well as reliability results from reliability characterization. Additionally, we investigated the impact of Deuterium on electrical parameters and reliability behavior.