Linear and non-linear optical properties of Ag-doped Ge₂Sb₂Te₅thin films estimated by single transmission spectra

Abstract

In this paper we have studied the effect of Ag addition on linear and non-linear optical properties of thermally evaporated (Ge 2 Sb 2 Te 5 ) 100−x Ag x (x=0, 1, 3 and 10) thin films (thickness ∼700 nm) from single transmission spectra. Energy dispersive spectroscopy, x-ray diffraction and Raman spectroscopy were used to verify the composition, amorphous nature and structure of the fabricated thin films respectively. Swanpoel's method was used to calculate the thickness (d), refractive index (n) and extinction coefficient (k). The refractive index and extinction coefficient were used to obtain all linear and non linear optical parameters. The compositional dependence of the refractive index, extinction coefficient, volume energy loss function, surface energy loss function, dielectric constant, dielectric loss function, optical conductivity and third order nonlinear optical susceptibility were determined. All these optical parameters have minimum values for 3% Ag-doped Ge 2 Sb 2 Te 5 (GST). The decrease in measured optical parameters up to 3% Ag doping is due to a decrease in the density of localized states in the mobility gap. The increase in the optical parameters at 10% Ag doping was ascribed to the distortion of the host lattice, because incorporation of Ag has been done at the expense of Ge, Sb and Te. The optical parameters of the GST films were found to be strongly dependent upon Ag content. The results revealed that 3% Ag-doped GST is a promising candidate for phase change optical storage applications.

Reduction of Rocksalt Phase in Ag -Doped Ge2Sb2Te5 : A Potential Material for Reversible Near-Infrared Window

“…It is highly unlikely that Ag will occupy the interstitial sites because of its larger size. The larger shift in the Ag (3d) spectrum of GST doped with 10% Ag suggests that there is more distortion in the lattice [28]. A shift is also observed in the Sb (3d) core-level spectra shown in Fig.…”

“…The VB spectra of GST thin film and thin film of GST doped with 3% Ag are similar in shape but an additional feature around 1.5 eV appears with Ag addition. The VB spectrum of thin film of GST doped with 10% Ag is totally different from that of GST thin film and that of thin film of GST doped with 3% Ag, which may be due to the distortion in the host lattice [28]. An additional feature appears in thin film of GST doped with 3% Ag, and is shifted toward the Fermi level in thin film of GST doped with 10% Ag.…”

“…(Ge 2 Sb 2 Te 5 ) 100−x Ag x (x = 0, 1, 3, 5, and 10) bulk alloys are prepared by a melt quenching technique [28] from highly pure (99.999%) constituent elements (Ge, Sb, Te, and Ag). Thin films of these alloys are deposited on glass substrates by a thermal-evaporation (Hind High Vacuum-BC-300) technique [28]. The thickness of the films is measured in situ by a digital thickness monitor (Hind High Vacuum DTM-101).…”

Composition dependent structural phase transition and optical band gap tuning in InSe thin films

“…Bulk alloys of In x Se 100- x ( x = 5, 10, 20, 30, 40 and 50) are prepared using melt quenching method [37, 38]. Here, x denotes the atomic-weight percentage of elements.…”

Single-crystalline Ag2Te nanorods prepared by room temperature sputtering of GeTe

“…The electrochemical reaction of Ag in amorphous chalcogenides of solid electrolytes has been investigated intensively because of the fundamental interests in anomalous diffusion [1], modified phase change characteristics [2,3], and optical properties [4][5][6] and also because of the potential device applications [7] such as RAM memories, sensors, and batteries. For example, the operation of conductive bridge RAM (CBRAM) devices [8,9] is based on the formation of conductive filaments via the electrochemical reaction of Ag ions.…”