Purification of HgI₂ Crystals from Physical Vapor Transport for Application as Radiation Detectors

Abstract

The establishment of a technique for mercury iodide (HgI2) purification and crystal growth is described, aiming this crystal future application as room temperature radiation semiconductor detectors. Repeated Physical Vapor Transport (PVT) technique was studied for purification and growth of the crystal. To evaluate the purification efficiency, measurements of the impurity concentration were made after each growth, analyzing the trace impurities. A significant decrease of the impurity concentration, resulting from the purification number, was observed. A significant improvement in the HgI2 radiation detector performance was achieved for purer crystals, growing the crystal twice by the PVT technique.

Purification and Crystal Growth of the Bismuth (III) Iodide-influence of Trace Impurities on the Crystal Quality

“…This type of detector has a large applicability as X ray and gamma ray spectrometer, operating at room temperature (McGregor & Hermon, 1997;Martins et al, 2012;Oliveira et al, 2004). Layered semiconductor materials have a number of properties that make them attractive for such application.…”

Synthesis and growth of HgI2 nanocrystals in a glass matrix: Heat treatment

“…6 Other studies have obtained HgI 2 using polycrystalline films produced by thermal evaporation, 7 spray pyrolysis, 8 physical vapor deposition, 9 and casting. 10 Still other techniques such as Physical Vapor Transport (PVT) 11,12 and solvent evaporation 13,14 are used to grow macroscopic HgI 2 crystals with dimensions in millimeters or centimeters. However, few studies report HgI 2 NC growth.…”

Purificação e preparação do cristal semicondutor de iodeto de bismuto para aplicação como detector de radiação

“…Assim, a partir do final da década de 80, compostos semicondutores que operam à temperatura ambiente têm atraído considerável atenção como possíveis alternativas ao silício e germânio 4,5,6 e que apresentem a vantagem de não operar sob refrigeração. Compostos semicondutores como Iodeto de bismuto (BiI 3 ), arseneto de gálio (GaAs), iodeto de mercúrio (HgI 2 ), iodeto de chumbo (PbI 2 ), telureto de cádmio e zinco (CdZnTe) e brometo de tálio (TlBr), para utilização como detectores de radiação 1,3,6,7,8 .…”

“…Cada uma dessas etapas afeta a qualidade cristalina e pode introduzir defeitos e imperfeições, deteriorando a resposta nuclear do detector [1][2][3][4][5]9,10 .…”

“…A capacidade de crescer cristais para a fabricação de detectores, mantendo a pureza e a qualidade morfológicas adequadas, é, ainda, um desafio tecnológico. A densidade de impurezas armadilhadoras define o tempo de vida dos portadores de carga (elétrons e lacunas) e, com isso, afeta a sua eficiência no processo de coleta de portadores 3,4 .…”