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Master's Dissertation
DOI
10.11606/D.76.1997.tde-06122013-171513
Document
Author
Full name
Érika Regina Manoel Andreeta
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1997
Supervisor
Committee
Hernandes, Antonio Carlos (President)
Baldochi, Sonia Licia
Guimarães, Francisco Eduardo Gontijo
Title in Portuguese
Crescimento de cristais de HgI2,PbI2 e PbI2: HgI2 para aplicações em detetores de radiação Ionizante
Keywords in Portuguese
Cristais
Radiação ionizante
Semicondutores
Abstract in Portuguese
Neste trabalho realizamos o crescimento de monocristais de α-HgI2 e PbI2, utilizados na confecção de detectores de radiação ionizante (raio-x e raio gama) a temperatura ambiente, bem como o crescimento de PbI2:HgI2 com composição nominal de HgI2 variando de 600 ppm ate 50000 ppm. Utilizamos o método de sublimação repetida para a purificação do iodeto de mercúrio e o crescimento do mesmo foi realizado pelo método PVT - "Physical Vapor Transport". Cristais de PbI2 and PbI2:HgI2 foram crescidos pelo método Bridgman. Apesar das diferentes estruturas cristalinas do HgI2 e PbI2, encontramos um limite de solubilidade em tomo de 600 ppm do iodeto de mercúrio no iodeto de chumbo. Através das medidas de fotoluminescência obtivemos informações sobre a pureza e qualidade cristalina das amostras obtidas. A largura da banda proibida dos cristais foi determinada através da absorção óptica, sendo de 2.10 eV para o HgI2 e por volta de 2.3 eV para o PbI2 e os cristais de PbI2: HgI2. Medimos também a condutividade elétrica em função da temperatura em todas as amostras. O valor da condutividade elétrica a temperatura ambiente e de 10-13 Ω-1 cm-1 para o HgI2, 10-12Ω-1 cm-1 para o PbI2 e varia entre 10-11 e 10-14 Ω-1 cm-1 para os cristais de PbI2: HgI2. Os cristais de HgI2 e PbI2 obtidos possuem boa qualidade cristalina, pureza, altos valores de largura de banda proibida e baixos valores de condutividade elétrica; qualidades necessárias para o bom desempenho em detectores de radiação ionizante
Title in English
Crystal growth of HgI2, PbI2 and PbI2:HgI2 for applications of ionizing radiation detectors
Keywords in English
Crystals
Ionizing radiation
semiconductors
Abstract in English
In this work we describe the growth of α-HgI2 and PbI2 single crystals, that are used to produce high energy radiation detectors (x-ray and y-ray) at room temperature, as well as the growth of PbI2:HgI2 crystals with nominal composition of HgI2 varying from 600 ppm to 50000 ppm. We used the repeated sublimation method to purify the mercuric iodide, and the growth of this material was done using the "Physical Vapor Transport" - PVT method. PbI2 and PbI2:Hgh crystals were growth by Bridgman method. In spite of the difference between the PbI2 and Hgb structures, we found a solubility limit of about 600 ppm of the mercuric iodide in the lead iodide. Using photoluminescence measurements we got information about purity and crystalline quality of the obtained samples. The gap energy of these crystals was determined through optical absorption, these values are 2.1 eV for HgI2 and about 2.3 for PbI2 and PbI2: HgI2 crystals. We also made measurements of the temperature dependence of the electrical conductivity in the samples. The electrical conductivity values at room temperature are about 10-13 Ω-1 cm-1 for HgI2, 10-12Ω-1 cm-1 for PbI2 and in the range of 10-11 and 10-14 Ω-1 cm-1 for PbI2: HgI2 crystals. The HgI2 and PbI2 crystals obtained have good crystalline quality, purity, high values of gap energy and low values of electrical conductivity those are necessary properties to good performance detectors
 
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Publishing Date
2013-12-09
 
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