Photoconductivity and nonlinear optical features of novel Ag x Ga x Ge 1-x Se 2 crystals

Oxysulfide Ba5(VO2S2)2(S2)2 Combining Disulfide Channels and Mixed-Anion Tetrahedra and Its Third-Harmonic-Generation Properties

“…In non-oxides, the fluoride BaMgF4 42 has recently shown the highest direct UV-third harmonic generation conversion efficiency in a solid state system via pure χ (3) nonlinear process. In the chalcogenide phases AgxGaxGe1-xSe2, THG have been related to the anions coordination within (Ga, Ge)Se4 tetrahedra and their resulting dipole moments that define the optical nonlinearities 43 . In our case, we report interesting THG properties in a crystalline oxychalcogenide, which to the best of our knowledge is rather uncommon for this type of crystalline materials.…”

Raman Scattering Study of Mixed Quaternary AgxGaxGe1−xSe2 (0.167 ≤ x ≤ 0.333) Crystals

“…The birefringence, that is the difference of refractive indices for ordinary and extraordinary rays, n o − n e , at 1,064 nm increases gradually from 0.114 for AgGaGe 2 Se 6 to 0.149 for AgGaGe 5 Se 12 and exceeds substantially the birefringence of the parent AgGaSe 2 compound (0.022) . This is the reason for rising interest to the family of these quaternary compounds in the recent past …”

“…As already mentioned, apart from the crystallographic structure of mixed Ag x Ga x Ge 1− x Se 2 compounds, their nonlinear optical and photovoltaic properties, photoconductivity, and electronic band structure are well documented in the recent past . To the best of our knowledge, however, there are no reports on the transformation of phonon spectra of mixed Ag x Ga x Ge 1− x Se 2 crystals upon variation of composition x , despite of the fact that lattice dynamics properties of the end‐member compounds AgGaSe 2 and GeSe 2 were studied extensively both experimentally and theoretically.…”

Investigation of the Anisotropic Thermal Expansion Mechanism of AgxGaxGe1–xSe2 Crystals

“…A new γ-phase Ag x Ga x Ge 1−x Se 2 that belonged to the Fdd2 space group 5 (x = 0.25) was discovered when investigating the AgGaSe 2 -GeSe 2 phase diagram. 6 The experimental band gaps of Ag x Ga x Ge 1−x Se 2 (x = 0.333, 0.25, 0.2, 0.167) are 2.37, 2.37, 2.4, and 2.42 eV, respectively, 7,8 which fall in between AgGaS 2 (2.73 eV) and AgGaSe 2 (1.80 eV). 3,9 The nonlinear coefficients measured by second harmonic generation (SHG) are, respectively, d 31 = 33.4 pm/V; d 32 = 15.6 pm/V for AgGaGe 3 Se 8 , and d 31 = 25 pm/V; d 32 = 10.3 pm/V for AgGaGe 5 Se 12 .…”

“…A new γ-phase Ag x Ga x Ge 1– x Se 2 that belonged to the Fdd2 space group ( x = 0.25) was discovered when investigating the AgGaSe 2 -GeSe 2 phase diagram . The experimental band gaps of Ag x Ga x Ge 1– x Se 2 ( x = 0.333, 0.25, 0.2, 0.167) are 2.37, 2.37, 2.4, and 2.42 eV, respectively, , which fall in between AgGaS 2 (2.73 eV) and AgGaSe 2 (1.80 eV). , The nonlinear coefficients measured by second harmonic generation (SHG) are, respectively, d 31 = 33.4 pm/V; d 32 = 15.6 pm/V for AgGaGe 3 Se 8 , and d 31 = 25 pm/V; d 32 = 10.3 pm/V for AgGaGe 5 Se 12 . , The LDT of AgGaGe 5 Se 12 crystal exceeds 80 GW/cm 2 (50 fs, 1400 nm pulses), and the surface laser-induced damage threshold (LIDT) is about 220 MW/cm 2 (1.06 μm, 15 ns, 1 Hz) . AgGaGe 3 Se 8 and AgGaGe 5 Se 12 both have high NLO coefficient and LDT values which satisfy the application requirements for promising mid-IR NLO crystals.…”