Raman investigation with excitation of various wavelength lasers on porous silicon

Abstract

By varying the incident laser wavelength, the intrinsic Raman spectrum of porous silicon formed on nondegenerate p-type silicon is identified and used to determine the dependence of the average pore size and porosity on the depth of the porous silicon layer. It is found that with increasing layer depth, the average pore size and porosity decreases, which is contrary to that of porous silicon formed on degenerate n-type silicon. This may indicate a different formation mechanism for these two types of porous silicon.

Amorphousness‐like nature of nano‐crystalline polar semiconductors

“…The identified result by Raman spectroscopy is consistent with that by the Xray refraction (XRD) in bulk materials and in non-polar semiconductors, e.g., porous silicon (PS) [3] and Si nano-wires (NWs) [5]. The one of evidences for this consistence is that the Raman spectra can be described by micro-crystal model (MCM) setup on the crystal dispersion curve and the size confinement effect [3,7]. But for nano-crystalline polar semiconductor (NC-PSC) SiC nano-rods (RDs), their Raman spectra can not described by the MCM but the amorphous model (ACM) related to the PDOS [6].…”

“…As a result, the Raman spectrum of AMs is correlated the phonon density of states (PDOS) and appears as the consisting of several wide peaks [6]. The identified result by Raman spectroscopy is consistent with that by the Xray refraction (XRD) in bulk materials and in non-polar semiconductors, e.g., porous silicon (PS) [3] and Si nano-wires (NWs) [5]. The one of evidences for this consistence is that the Raman spectra can be described by micro-crystal model (MCM) setup on the crystal dispersion curve and the size confinement effect [3,7].…”

“…1. This is contracted sharply with that of PS [3], Si NWs [11] and CNTs [4] with size-distributed For example, the Raman frequency shift of SiNWs was about 17 cm -1 when the excitation wavelengths varied from 488 to 785 nm [11]. Note that the Raman spectrum of AMs is related to the PDOS [6] and the PDOS should not change with the sample sizes according the definition of PDOS, which also was recently confirmed by a theoretical calculation on the PDOS of Si with various sizes [12].…”

The dependence of hydrofluoric acid concentration during anodization on photoluminescence of porous silicon

“…But the anodization time is also varied in the literature. Further, there was no discussion on PL spectra [10].…”

Spontaneous Raman emission and tunable Stokes shift in porous silicon

“…The phonon peak broadens towards lower energy and shifts slightly. The line-shape asymmetry increases as the incident photon energy is increased [6][7][8][9][10][11][12][13][14][15][16]. while porous silicon sample is obtained by an electrochemical etching starting from p+ silicon wafer.…”