Impurity Doping in Silicon Nanowires (original) (raw)

Doping effects on the Raman spectra of silicon nanowires

Physical Review B, 2006

Un-doped, N-type, and P-type doped silicon nanowires ͑SiNWs͒ were grown at 460°C and 25 Torr via the vapor-liquid-solid ͑VLS͒ mechanism. The intensity ratio of anti-Stokes/Stokes ͑I AS / I S ͒ peaks is used as an index of the sample temperature. Different SiNWs exhibit different Raman frequency shifts because their compressive stresses due to heating differ. The slopes of the I AS / I S peak ratio versus the Raman frequency for boron-doped, un-doped, phosphorous-doped SiNWs, and bulk Si are −0.078, −0.036, −0.035 and −0.02 per cm −1 , respectively. The different slopes reveal the different heating-induced compressive stresses in the SiNWs with different dopants and bulk Si.

Impurity doping in silicon nanowires synthesized by laser ablation

Applied Physics A, 2008

or phosphorus (P) doped silicon nanowires (SiNWs) were synthesized by laser ablation. Local vibrational modes of B were observed in B-doped SiNWs by micro-Raman scattering measurements at room temperature. Fano broadening due to a coupling between the discrete optical phonon and a continuum of interband hole excitations was also observed in the Si optical phonon peak for B-doped SiNWs. An electron spin resonance signal due to conduction electrons was observed only for P-doped SiNWs. These results prove that B and P atoms were doped in substitutional sites of the crystalline Si core of SiNWs during laser ablation and electrically activated in the sites. PACS 81.07.Vb · 81.16.Mk · 63.22.+m · 65.80.+n · 78.30.Am

First-principles study of vibrational modes and Raman spectra in P-doped Si nanocrystals

Physical Review B, 2014

We have studied the vibrational modes and Raman spectra of P-doped Si nanocrystals using pseudopotential density functional theory and the Placzek approximation. We find that Si nanocrystal vibrations are largely unaffected by the introduction of P dopants. However, the Raman spectra of doped nanocrystals are enhanced relative to those of pristine nanocrystals, and demonstrate a strong dependence on dopant position. Thus, Raman has the potential of being developed as a tool for probing the location of the dopant within the nanocrystal. Our analysis shows that vibrational modes involving atoms in the vicinity of the dopant give the largest contributions to the Raman spectra.

First and second-order Raman scattering in Si nanostructures within silicon nitride

Applied Physics Letters, 2010

First and second-order Raman analysis on annealed silicon nitride films is reported. Possible formation of amorphous Si nanoparticles after an intermediate treatment is deduced from the occurrence of a resonant spectrum. After nucleation of Si nanocrystals, with a model description of the first-order spectra it is possible to access information regarding mean radius, size dispersion, and crystalline phase fraction consistent with the fundamental data derived from microscopy. Substantial increase in second to first order intensity ratio is also observed: Enhanced electron-phonon coupling in both amorphous and crystalline Si nanoparticles is suggested.

IAETSD-Structural and Electronic properties of doped SiliconNanowire

Electronic and structural properties of Silicon Nanowire (SiNW) when doped with Al and P atoms are obtained from simulation studies have been reviewed . The bandgap , density of states and Structural property of Sillicon Nanowire has been compared when this nanowire is doped with phosphrous and aluminium atoms. We observed that decrease in bandgap increases the metallic property of silicon. Total energy is maximum then the structure is least stable . So we can say that total energy is inversely proportional to stability. In density of states , we clearly see the decline in DOS/Ev with the increase of doping Al and P atoms. In this paper , we have discussed all the electronic and structural properties.

Doping in silicon nanostructures

Physica Status Solidi (A) Applications and Materials Science, 2007

We report on an ab initio study of the structural, electronic and optical properties of boron and phosphorous doped silicon nanocrystals. The scaling with the Si-nanocrystal size is investigated for both the neutral formation energies (FE) and the impurity activation energies. Both these energies scale with the nanocrystal inverse radius. The optical properties reveal the existence of new absorption peaks in the low energy region related to the presence of the impurity. The effects of B and P co-doping show that the formation energies are always smaller than those of the corresponding single-doped cases due to both carriers compensation and minor structural distortion. Moreover in the case of co-doping the electronic and optical properties show a strong reduction of the band gap with respect to the pure silicon nanocrystals that makes possible to engineer the photoluminescence properties of silicon nanocrystals.

Raman study of Fano interference in p-type doped silicon

Journal of Raman Spectroscopy, 2010

As the silicon industry continues to push the limits of device dimensions, tools such as Raman spectroscopy are ideal to analyze and characterize the doped silicon channels. The effect of intervalence band transitions on the zone center optical phonon in heavily p-type doped silicon is studied by Raman spectroscopy for a wide range of excitation wavelengths extending from the red (632.8 nm) into the ultra-violet (325 nm). The asymmetry in the one-phonon Raman lineshape is attributed to a Fano interference involving the overlap of a continuum of electronic excitations with a discrete phonon state. We identify a transition above and below the one-dimensional critical point (EΓ 1 = 3.4 eV) in the electronic excitation spectrum of silicon. The relationship between the anisotropic silicon band structure and the penetration depth is discussed in the context of possible device applications.