Investigation of non-uniformity and inclusions in 6LiInSe2 utilizing Laser Induced Breakdown Spectroscopy (LIBS)

Impurity analysis and compositional distribution studies have been conducted on a crystal of LiInSe 2 , a compound semiconductor which recently has been shown to respond to ionizing radiation. IR microscopy and laser induced breakdown spectroscopy (LIBS) revealed the presence of inclusions within the crystal lattice. These precipitates were revealed to be alkali and alkaline earth elemental impurities with non-uniform spatial distribution in the crystal. LIBS compositional maps correlate the presence of these impurities with visual color differences in the crystal as well as a significant shift of the band gap. Further, LIBS revealed variation in the ratio of I-III-VI2 elemental constituents throughout the crystal. Analysis of compositional variation and impurities will aid in discerning optimal synthesis and crystal growth parameters to maximize the mobility-lifetime product and charge collection efficiency in the LiInSe 2 crystal. Preliminary charge trapping calculations have also been conducted with the Monte Carlo N-particle eXtended (MCNPx) package indicating preferential trapping of holes during irradiation with thermal neutrons.