Electron spin resonance in P-doped Si nanocrystals/SiC stacked structures with various dot sizes

Doping in semiconductor nanocrystals have a significant impact on electronic structures and the relative studies are needed in order to deeply understand the doping effect in nanoscale. Here, we fabricate un-doped and P -doped Si nanocrystals (Si NCs)/Silicon carbide (SiC) multilayers with various dot sizes (8, 4 and 2 nm). Low temperature (77 K) electron spin resonance spectra are measured to study the electronic structures before and after P doping. It is found that the g value is kept at 2.005 for un-doped Si NCs samples, which is independent of the dots size, indicating the existence of dangling bonds at the surface of Si NCs. After P doping, for samples with dot size of 8 nm, the g value is 1.998, which is assumed to the conduction electrons. It suggests that P impurities are introduced into the inner of Si NCs substitutionally to provide the conduction electrons. However, with the reduction of dot size, the signals with g = 2.004, which is associated with the Si vacancies, are identified in P -doped samples, while the peak-to-peak linewidth Delta Bpp is narrowed with the dots size decreasing. It shows the possibility to apply P-doped Si NCs/SiC multilayers with ultra-small dot sizes into Si-based spintronics.

Automated summary

We fabricated un-doped and P-doped Si nanocrystals/Silicon carbide multilayers with different dot sizes (8, 4 and 2 nm) and measured low temperature (77 K) electron spin resonance spectra to investigate the doping effect on electronic structures. The results showed that the g value of un-doped Si nanocrystals remained at 2.005, indicating the presence of dangling bonds on the surface. After P doping, the g value decreased to 1.998 in samples with a dot size of 8 nm, suggesting the introduction of conduction electrons by P impurities. With the reduction of dot size, signals associated with Si vacancies were identified in P-doped samples, indicating the potential application of P-doped Si nanocrystals/SiC multilayers with ultra-small dot sizes in Si-based spintronics.