Mercuric iodide for room temperature radiation detectors. Synthesis, purification, crystal growth and defect formation

Abstract

A critical review of the recent progress in understanding the major phenomena involved in growth of large mercuric iodide crystals for room temperature X- and γ-ray detectors is presented. Since physical vapour transport (PVT) has been established as the best method to grow these crystals, kinetics and mechanisms of growth by PVT are discussed in detail. Particular attention is given to the elucidation of the relationship between the kinetics of growth and the nature and distribution of defects in the as-grown crystals. It is shown that various types of defects which may deteriorate the detector performance—such as impurities, nonstoichiometry, mosaicity, thermal strain, striations—can efficiently be controlled during growth. Other defects are, however, introduced during the post-growth processing of the crystals. The ability to identify and differentiate between these two groups of defects is the major achievement of the recent research on this difficult material.