Suppression of Narrow-Line Defects in Organic 4-Dimethylamino-N-methyl-4-stilbazolium Tosylate Crystals through Uninterrupted Solution Stirring during Growth Process

Abstract

We investigated narrow-line defects (NLDs) as a possible cause of the degradation of the bulk laser-induced-damage tolerance of organic 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystals, which are used for high-power terahertz (THz) application. NLDs are bulk defects and can be classified as planar defects along a-axis. Since the NLDs were considered to be caused by instabilities in the solution environment during the crystal growth, we introduced solution stirring throughout the growth process. Our experimental results showed that solution stirring was effective in decreasing the number of NLDs in DAST crystals in comparison with the conventional growth process. We also discuss the mechanism of NLD formation and the effect of solution stirring from the results of chemical-etching experiments.