Growth improvement of AgGaSe₂ crystal using the vertical Bridgman technique with steady ampoule rotation and its characterization

Abstract

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.