Preparation of SiNWs:B and the Effect of Doping B on the Resistivity of SiNWs

Background: Silicon nanowires (SiNWs) represent a novel semiconductor material distinguished by unique physical attributes that diverge from those of bulk silicon, garnering significant interest and becoming a focal point in semiconductor research. Boron has rich and adjustable physical, chemical, and electrical properties and has received widespread attention in the study of doping elements in recent years. The controlled doping of SiNWs is crucial for its application, as doping technology can enhance the optoelectronic properties of silicon nanowires, making them more competitive in practical applications. Objective: This study aims to synthesize SiNWs and B-doped silicon nanowires (SiNWs:B) using non-toxic sources, such as SiO2 and Si, and to explore their photoluminescence (PL) and IV properties. Methods: This study utilized the thermal evaporation method to fabricate boron-doped silicon nanowires (SiNWs: B). In the experiment, B2O3 was used as the dopant, La as the catalyst, and SiO2 and Si as the raw materials. These materials were completely mixed and placed in the heating center of the tube furnace. The evaporation source was heated to 1280°C under a nitrogen (N2) atmosphere. During the heating process, Si, SiO2, La, and B were evaporated into an atomic fog and collided with N2 atoms in the carrier gas, resulting in the loss of energy of thermal motion. Among them, the La and Si atomic fog rapidly cooled to form La-Si co-melting droplets. When the co-melting droplets absorbed Si atoms and reached saturation, the excess Si atoms separated out due to their inability to continue dissolving in the co-melting droplets, forming internal Si single-crystal nanowires. At the same time, lower-density SiO2 formed a SiO2 shell around Si nanowires, facilitating their growth along the one-dimensional direction. In addition, boron atoms were naturally diffused into the silicon nanowires as dopants and formed a stable doping distribution after cooling. The photoluminescence and I-V characteristics of the samples were performed. Results: PL spectra revealed two emission bands at 347 nm and 393 nm under a 239 nm excitation wavelength for both SiNWs and SiNWs:B. I-V measurements indicated that at a B doping concentration of 3 wt%, SiNWs:B samples exhibited the lowest resistivity, reaching 8.023 × 106 Ω·cm, providing insights into the electrical properties of B-doped materials. Conclusion: The PL spectra demonstrated that boron doping concentrations minimally affected the PL properties of silicon nanowires. I-V analysis revealed that resistivity decreased initially with increasing B concentration and then increased. Notably, at a B doping concentration of 3 wt%, the resistivity of SiNWs:B was at its lowest. Compared to undoped SiNWs, B-doped samples showed enhanced conductivity, underscoring their potential in optoelectronic device applications.