Crystal Growth, Characterization, and Thermal Annealing of Nonlinear Optical Crystals AgGaGe_nSe_2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) for Mid-infrared Applications

Abstract

The new quaternary single crystals AgGaGe n Se 2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) have high nonlinear optical property and can be used for mid-IR laser applications in high power. However, only AgGaGe 3 Se 8 and AgGaGe 5 Se 12 have been grown on a large scale and studied in detail. In this work, the AgGaGe n Se 2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) crystals (Φ 20 mm × 40 mm and Φ 40 mm × 100 mm) were grown by the modified Bridgman method. The crystal structure was studied by X-ray diffraction and the Rietveld refinement method. The composition and morphology were characterized by scanning electron microscopy and metallurgical microscopy. The chemical state and vibration modes of surface elements were characterized by X-ray photoelectron spectroscopy and Raman spectra, and the electrical property was investigated by the Hall effect measurement, which indicates that all the single AgGaGe n Se 2(n+1) crystals are n-type semiconductors. The transmittance of all asgrown AgGaGe n Se 2(n+1) crystal wafers exceed 65% in the transparent range, and the band gap increases from 2.05 eV for AgGaGe 1.5 Se 5 to 2.14 eV for AgGaGe 9 Se 20 . Besides, after being annealed in two different conditions, the wafers show different changes. We discovered a special decomposition phenomenon during the annealing process and found the more appropriate annealing method at last. In addition, the absorption peaks at 4.2, 10, and 14.9 μm of wafers have been nearly eliminated, and the quality of most crystals has been improved.

Crystal Growth, Thermal Treatment, and Characterization of Nonlinear Optical Crystal LiGa0.5In0.5Se2 for Mid-infrared Applications

“…As shown in Figure a, the wafers of crystal-I and crystal-II show low visible-light transmission and have red color under white light. Thermal treatment in our previous study has been proven to be an effective way to ameliorate this defect. − In this work, we chose two thermal treatment methods, including vacuum annealing and quenching. For crystal-I, after vacuum annealing at 873 K and 1023 K, the wafers all turned out to be black and brittle (Figure b), and the EDS data in Table show that the Se content of the wafer surface after 873 K annealing abnormally increases; this may be caused by the decomposition of selenide, and then the Se atom diffuses to the wafer surface.…”

Crystal Growth, Characterization, and Properties of Nonlinear Optical Crystals of LixAg1–xGaSe2 for Mid-Infrared Applications

“…Thus, the properties of materials can be adjusted by ion substitution to form a solid solution or compound to achieve such an equilibrium. AgGaGe n S 2( n +1) and AgGaGe n Se 2( n +1) are quaternary solid solution crystals obtained by replacing Ga 3+ with Ge 4+ in AgGaS 2 and AgGaSe 2 crystals, − which increased the LIDT several times while maintaining the large NLO coefficient.…”

Growth and Variable Temperature Hall Effect Study of SrPb3Br8Crystal with Low Phonon Energy

“…In the present work, we successfully grew the SrPb 3 Br 8 single crystal via vertical Bridgman method, [23,24] and used X-ray diffraction and X-ray photo-electron spectroscopy tests to detect the phase composition of the single crystal and the element states of the surface of the processed wafers, respectively. Then, Raman and transmission tests were carried out to investigate the phonon energy and optical properties of the samples.…”