Surface-Enhanced Raman Scattering on a Chemically Etched ZnSe Surface

Abstract

We report the observation of surface-enhanced Raman scattering (SERS) from a chemically etched ZnSe surface using 4-mercaptopyridine (4-MPy) as probe molecules. A thin film of ZnSe is grown by molecular beam epitaxy (MBE) and then etched using a strong acid. Protrusions of hemiellipsoidal nanoparticles are observed on the surface. Using the results of the Mie theory, we controlled the size of the nanoparticles to overlap significantly with maximum efficiency of near-field plasmon enhancement. In the Raman spectrum, we observe large enhancements of the a1, b1, and b2 modes when 4-MPy molecules are adsorbed on the surface using a 514.5 nm laser for excitation, indicating strong charge-transfer contributions. An enhancement factor of (2 × 106) is observed comparable to that of silver nanoparticles. We believe this large enhancement factor is an indication of the coupled contribution of several resonances. We propose that some combination of surface plasmon, charge transfer, and band-gap resonances is most likely the contributing factor in the observed Raman signal enhancement because all three of these resonances lie close to the excitation wavelength.

A Novel Ultra‐Sensitive Semiconductor SERS Substrate Boosted by the Coupled Resonance Effect

“…From porous ZnO nanosheets, [15] TiO 2 photonic microarrays, [16] CuTe quantum dots, [17] chemically etched ZnSe, [18] and single Cu 2 O superstructure particles [19] to urchin-like W 18 O 49 , [20] MoO 3−x @MoO 3 nanosheets, [21] MoO 3−x quantum dots, [22] and oxygen-incorporating MoS x O y , [23] two types of methods are generally used to improve the SERS performance of semiconductor substrates: morphology design and element doping. As an increasing number of researchers are engaging in the study of semiconductor SERS substrates, research achievements regarding semiconductor SERS substrates have grown exponentially in recent years.…”

Rapid and label-free Raman detection of azodicarbonamide with asthma risk

“…2A shows the SERS spectrum of ADA at the 1 × 10 −4 M concentration mixed with Au@Ag NPs and the normal Raman spectrum of ADA solid powder. The differences between normal Raman and SERS spectra could be due to both the electromagnetic (i.e., localized surface plasmon resonance) and chemical (i.e., charge transfer) interactions between analytes and substrate surfaces [39]. It is well known, as conducting SERS experiment, some IR-active bands could be seen [40,41], such as the SERS band at 1028 cm −1 in this work.…”

Noble‐Metal‐Free Materials for Surface‐Enhanced Raman Spectroscopy Detection

“…In general, most LSPRs of semiconductors are observed in the long‐wavelength region due to a relatively lower electron density in the conduction band compared to metals. Thus the Raman enhancement of semiconductors is usually attributed to the chemical mechanism, and the enhancement factor is somewhat lower than those observed with noble metals . Recently, it was found that the free carrier concentrations can be tuned by doping and phase transitions, allowing engineering of LSPR frequencies to visible regions .…”

“…[16] Since then, av ast variety of semiconductor materials such as Fe 3 O 4 , [17] a-Fe 2 O 3 , [18] Cu 2 O, [19] CuO, [20] Ag 2 O, [21] CdS, [22] ZnS, [23] CdTe, [24] TiO 2 , [10,25] PbS, [26] and AgS [27] were introduced and used as SERS-active substrates. Benefiting from the explosive development of nanoscience and nanotechnology,r ecent studies on TiO 2 , [28] CdTe, [29] Cu 2 O, [30] and ZnSe [31] have demonstrated large enhancement factors greater than 10 6 ,w hichi s comparable to the noble metal nanostructures.…”