Crystals for a semiconductor radiation detector and method for making the crystals

Abstract

A method for a growing solid-state, spectrometer grade II-VI crystal using a high-pressure hydrothermal process including the following steps: positioning seed crystals in a growth zone of a reactor chamber; positioning crystal nutrient material in the nutrient zone of the chamber; filling the reactor with a solvent fluid; heating and pressuring the chamber until at least a portion of the nutrient material dissolves in the solvent and the solvent becomes supercritical in the nutrient zone; transporting supercritical from the nutrient zone to the growth zone, and growing the seed crystals as nutrients from the supercritical fluid deposit on the crystals.

1 . A solid-state, spectrometer grade crystal, wherein the crystal is formed by a process comprising: 
 positioning a seed crystal in a growth zone of a reactor chamber;    positioning crystal nutrient material in the nutrient zone of the reactor chamber;    filling the reactor chamber with a solvent fluid;    heating and pressuring the reactor chamber until at least a portion of the nutrient material dissolves in the solvent and the solvent becomes supercritical with the nutrient material in the nutrient zone;    transporting the supercritical solvent from the nutrient zone to the growth zone, and    growing the crystal as nutrients from the supercritical solvent deposit on the seed crystal.    
   
   
       2 . A crystal as in  claim 1  wherein the seed crystal is a CdTe or CZT crystal.  
   
   
       3 . A crystal as in  claim 1  having a size greater than 0.5 cm 3 .  
   
   
       4 . A crystal as in  claim 1  having a size greater than 3 cm 3 .  
   
   
       5 . A crystal as in  claim 1  having a resistivity of at least 10 9  Ω-cm.  
   
   
       6 . A crystal as in  claim 1  having a resistivity in a range of 10 9  Ω-cm to 10 11  Ω-cm.  
   
   
       7 . A crystal as in  claim 1  wherein the processes includes adding a dopant selected from one of Cl, Ge, Sn and In to the nutrient.  
   
   
       8 . A crystal as in  claim 1  wherein the crystal comprises a portion of at least one of a gamma radiation detector, a gamma ray spectrometer, an area search device, a gamma ray imaging array, a direct conversion x-ray detector, a dual- or multi-energy x-ray detector, an x-ray spectrometer, an x-ray imaging array and an x-ray computed tomography system.  
   
   
       9 . A crystal as in  claim 1  wherein said nutrient comprises Cd 1−x Zn x Se y Te 1−y , where 0≦x,y≦1.  
   
   
       10 . A crystal as in  claim 1  wherein growing the seed crystal is performed at a growth zone temperature of at least 450° C. and a chamber pressure of at least 2 kbar.  
   
   
       11 . A crystal as in  claim 10  wherein the growth zone temperature is at least 550° C. or the chamber pressure is at least 5 kbar.  
   
   
       12 . A crystal as in  claim 10  wherein the growth zone temperature is at least 375° C. and the chamber pressure is at least 700 bar.  
   
   
       13 . A crystal as in  claim 1  wherein the process further comprises adding a dopant to the nutrient material, wherein the dopant is selected from a group consisting of Cl, Ge, Sn, In, B, Al, Ga, Tl, C, Si, Pb, N, P, As, Sb, Bi, F, Br, I, Be, Mg, Ca, Sr, Ba,  0  and S.  
   
   
       14 . A crystal as in  claim 1  wherein the process further comprises adding a mineralizer to the solvent wherein the mineralizer comprises at least one of alkali hydroxide and carbonate.  
   
   
       15 . A crystal as in  claim 1  wherein the solvent comprises at least one of an ammonia, ethylenediamine, methanol and ether.  
   
   
       16 . A crystal as in  claim 1  wherein positioning the seed crystal includes positioning a plurality of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) seed crystals.  
   
   
       17 . A solid-state, spectrometer grade II-VI crystal, wherein the crystal is formed by a process comprising: 
 positioning a seed crystal in a growth zone of a reactor chamber;    positioning crystal nutrient material in the nutrient zone of the reactor chamber, wherein a baffle in the reactor chamber separates the nutrient zone and the growth zone;    filling the reactor chamber with a solvent fluid;    heating and pressuring the reactor chamber until at least a portion of the nutrient material dissolves in the solvent and the solvent becomes supercritical with the nutrient material in the nutrient zone;    transporting the supercritical solvent from the nutrient zone, through the baffle and to the growth zone, and    growing the seed crystals as nutrients from the supercritical solvent deposit on the crystals at a growth zone temperature of at least 375° C. and at a reactor pressure at least 700 bar.    
   
   
       18 . A crystal as in  claim 17  wherein the seed crystal comprises Cd 1−x Zn x Se y Te 1−y , where 0≦x,y≦1.  
   
   
       19 . A crystal as in  claim 17  wherein the nutrient material includes at least one of CZT and CdTe.  
   
   
       20 . A crystal as in  claim 17  wherein the step of heating the reactor chamber includes heating the reactor chamber such that the nutrient zone is warmer than the growth zone.