Growth improvement of AgGaSe<SUB>2</SUB> crystal using the vertical Bridgman technique with steady ampoule rotation and its characterization

The polycrystalline charges were successfully synthesized from high purity elemental starting materials by the vapor transport method with the mechanical and melt temperature oscillation. High pure, single phase, free of voids and crack-free AgGaSe2 single crystals have been grown by the vertical Bridgman technique with steady ampoule rotation. The structural perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. AgGaSe2 has been studied using differential scanning calorimetry (DSC) technique. The stoichiometric composition of AgGaSe2 was measured using energy dispersive spectrometry (EDS). The insignificant change in atomic percentages of Ag, Ga and Se along the ingot further reveals that the composition throughout its length is fairly homogeneous. The band gap and melting point along the length of the ingot are studied. The structural and compositional uniformities of AgGaSe2 were studied using micro-Raman scattering spectroscopy at room temperature. The insignificant change in the FWHM of the Γ 1(W1) measured at different regions of the crystal further reveals that the composition throughout its length is fairly uniform. As grown single crystal shows very high IR transmission of ~72% in the spectral range 4000-530 cm-1