Raman investigation of InSe doped with GaS

The Impact of Doping on the Anti-Resonance Effects of A11g Mode of InSe

“…In this report, the anti-resonance behavior of nonpolar 1 1 g A (116 cm -1 ) mode of pure InSe and InSe doped with GaS which was observed previously will be discussed [24].…”

“…For details of the crystal preparation, experimental setup, and its geometry see Ref. [24] and for chemical analysis see Refs. [34,35].…”

“…However, in some materials, pronounced decrease in Raman scattering efficiency is observed, before the onset of resonance Raman enhancement [25][26][27]. In InSe, a monotonic decrease in scattering efficiency of nonpolar optical mode of 1 1g A symmetry (116 cm -1 ) is observed as photon energy approaches excitonic energy [24]. This decrease in the Raman scattering cross-section is referred to as anti-resonance [26].…”

“…The lowest direct and indirect bandgap in InSe at 300 K are at 1.256 and 1.187 eV, respectively [19]. The energy of the hyperbolic exciton near the M1 saddle point is 2.77 eV at 300 K. The normal modes of vibration are represented as, Raman scattering is a powerful technique for probing lattice vibration [18][19][20][21][22][23][24][25][26][27][30][31][32][33], resonance Raman scattering (RRS) [18,24] and anti-resonance effect [26] in the layered semiconductor materials. Numerous researchers have studied anti-resonance effects for CdS semiconductor [25,26] and have found that cancellation of scattering amplitude occurs near 2.41 eV.…”

“…Ashokan et al [23] have formulated theory of RRS in a quasi-two-dimensional InSe near excitonic transition. Zolfaghari et al have studied the effect of doping of InSe with GaS in a systematic way [24]. They found that as a result of GaS doping InSe: (i) there is a shift in the excitonic energy E1 toward higher energy values, (ii) all modes exhibit broadening indicating topological disorder.…”