MERCURIC IODIDE CRYSTAL GROWTH AND DOPING FOR ENHANCED X-RAY DETECTION

Abstract

Mercuric iodide (HgI₂) has emerged as a promising semiconductor material for room-temperature X-ray and gamma-ray detection applications due to its large bandgap, high atomic numbers, and excellent photon stopping power. Despite these advantages, persistent challenges in crystal growth techniques and material performance have limited its widespread adoption. This review examines recent advances in HgI₂ crystal growth methodologies, focusing particularly on the physical vapor transport (PVT) method, solution growth techniques, and melt-based approaches. We analyze how various doping strategies—including monovalent (Na⁺, Ag⁺), divalent (Cd²⁺, Pb²⁺), and trivalent (Bi³⁺, In³⁺) impurities—influence the electrical properties, charge transport mechanisms, and detector performance. The review synthesizes experimental findings from the past decade, identifying correlations between growth conditions, dopant concentrations, crystal quality, and X-ray detection efficiency. Our analysis indicates that carefully controlled doping, particularly with Cd and Bi at concentrations of 10-100 ppm, substantially enhances detector performance by reducing polarization effects and improving charge carrier mobility. Based on this comprehensive assessment, we propose optimized growth and doping parameters for next-generation HgI₂-based radiation detectors with improved sensitivity, energy resolution, and operational stability. Keywords: Mercuric iodide; crystal growth; doping; X-ray detection; semiconductor.