Synthesis, structure, linear and nonlinear optical properties of noncentrosymmetric quaternary diamond-like semiconductors, Cu2ZnGeSe4 (CZGSe) and the novel Cu4ZnGe2Se7

Crystal structure, electronic structure, and optical properties of the novel Li4CdGe2S7, a wide-bandgap quaternary sulfide with a polar structure derived from lonsdaleite

“…The cationsulfur bonds containing S4 are the longest in each of their respective tetrahedra. Similar subtle structural distortions have been observed in other I 4 -II-IV 2 -VI 7 compounds, for example, Cu 4 FeGe 2 S 7 , Cu 4 CoGe 2 S 7 , Li 4 CdSn 2 S 7 , Cu 4 Mn-Ge 2 S 7 , and Cu 4 ZnGe 2 Se 7 (Craig et al, 2020;Zhang, Stoyko et al, 2020;Glenn et al, 2021;Sinagra et al, 2021).…”

“…Using two slightly dissimilar r 0 for the Cd-S bond that are provided by two different sources, the two G values calculated for both Li 4 CdGe 2 S 7 and Li 2 CdGeS 4 , 0.08 (or 0.09) and 0.07 (or 0.09), respectively, are well within the range indicative of reasonable structural strain (0.05 < G < 0.2) (Table 7). These values are lower than those calculated for similar compounds reported by our group, for example, Cu 4 ZnGe 2 Se 7 , Cu 2 Mn-GeS 4 , and Cu 4 MnGe 2 S 7 , which range from 0.16 to 0.20 (Sinagra et al, 2021;Glenn et al, 2021). These results, in addition to the excellent refinement statistics of the singlecrystal structure, give us confidence in our structure solution and refinement for the title compound.…”

“…Li 4 HgSn 2 Se 7 possesses an even narrower bandgap of 2.10 eV, and exhibits a greater PM SHG response of 3.6 Â AGS at = 2.09 mm (Guo et al, 2019). While Cu 4 ZnGe 2 Se 7 displays a very weak SHG response (Sinagra et al, 2021), Cu 4 MnGe 2 S 7 has a second-order NLO susceptibility, (2) , of 2.33 AE 0.86 pm V À1 , assessed at the static limit (Glenn et al, 2021). Recently, we have demonstrated that Li 4 CdSn 2 S 7 is the best I 4 -II-IV 2 -VI 7 IR-NLO candidate material to date, with an excellent balance of properties, an optical bandgap of 2.59 eV, an exceptional LIDT of 12.5 Â AGS ( = 1.064 mm, = 30 ps), and a (2) value of 35 pm V À1 at the static limit (Zhang, Stoyko et al, 2020).…”

Phase Matching, Strong Frequency Doubling, and Outstanding Laser-Induced Damage Threshold in the Biaxial, Quaternary Diamond-like Semiconductor Li4CdSn2S7

“…It should be noted that Li 2 CdSiS 4 was reported by Li et al to have an SHG response equivalent to AGS, but this was at 2.09 μm (not the static limit) with a reference of unknown quality . Li 4 CdSn 2 S 7 is on par with the commercialized AGS in terms of χ (2) , and it outshines all of the commercialized lithium sulfides, LGS, LGSe, LIS, and LISe. ,,,, The few quaternary DLSs with higher χ (2) values have narrow bandgaps (e.g., Cu 2 CdSnS 4 and Cu 2 ZnGeSe 4 ) and relatively low LIDTs. It is important to note that the optical-quality AGSe that we use as a reference typically yields an SHG response twice as strong as our homemade microcrystalline sample. , Therefore, the excellent χ (2) values of Li 4 CdSn 2 S 7 and Li 2 CdSiS 4 may actually be markedly underestimated.…”

“…18 Li 4 CdSn 2 S 7 is on par with the commercialized AGS in terms of χ (2) , and it outshines all of the commercialized lithium sulfides, LGS, LGSe, LIS, and LISe. 4,10,59,72,75 The few quaternary DLSs with higher χ (2) values have narrow bandgaps (e.g., Cu 2 CdSnS 4 76 and Cu 2 ZnGeSe 4 77 ) and relatively low LIDTs. It is important to note that the optical-quality AGSe that we use as a reference typically yields an SHG response twice as strong as our homemade microcrystalline sample.…”