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 method for a growing solid-state, spectrometer grade II-VI crystal comprising: 
 positioning seed crystals 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 pressurizing the chamber until at least a portion of the nutrient material dissolves in the solvent and the solvent becomes supercritical;    transporting dissolved nutrient from the nutrient zone to the growth zone, and    growing the seed crystals as nutrients from the supercritical fluid deposit on the crystals.    
   
   
       2 . The method of  claim 1  wherein said seed crystals comprise Cd 1-x Zn x Se y Te 1-y , where 0≦x,y≦1.  
   
   
       3 . The method of  claim 1  wherein in the step of growing the seed crystals a growth zone temperature is at least 450° C. and a reactor pressure is at least 2 kbar.  
   
   
       4 . The method of  claim 1  wherein in the step of growing the seed crystals a growth zone temperature is at least 550° C. or the reactor pressure is at least 5 kbar.  
   
   
       5 . The method of  claim 1  wherein in the step of growing the seed crystals at a growth zone temperature of at least 375° C. and at a reactor pressure at least 700 bar.  
   
   
       6 . The method of  claim 1  further comprising 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, O and S.  
   
   
       7 . The method of  claim 1  further comprising adding a mineralizer to the solvent wherein the mineralizer comprises at least one of alkali hydroxide and carbonate.  
   
   
       8 . The method of  claim 1  wherein the solvent is at least one of an ammonia, ethylenediamine, methanol and ether.  
   
   
       9 . The method of  claim 1  wherein positioning seed crystals includes positioning a plurality of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) seed crystals.  
   
   
       10 . The method of  claim 1  wherein the reactor chamber is divided by a porous baffle into the growth zone and the nutrient zone.  
   
   
       11 . The method of  claim 1  wherein the crystal nutrient material includes at least one of CZT and CdTe.  
   
   
       12 . The method of  claim 1  wherein the step of heating the reactor chamber includes heating the reactor chamber such that the nutrient zone is warmer than the growth zone.  
   
   
       13 . The method of  claim 1  wherein transporting the dissolved nutrient includes passing the nutrient through a baffle between the nutrient zone and the growth zone.  
   
   
       14 . A method for a growing solid-state, spectrometer grade II-VI crystal comprising: 
 positioning seed crystals in a growth zone of a reactor chamber;    positioning crystal nutrient material in the nutrient zone of the chamber, wherein a baffle separates the nutrient zone from the reactor chamber;    filling the reactor chamber with a solvent fluid;    heating and pressurizing the reactor chamber until at least a portion of the nutrient material dissolves in the solvent and the solvent becomes supercritical;    transporting dissolved nutrient from the nutrient zone, through the baffle, to the growth zone, and    growing the seed crystals as nutrients from the supercritical fluid deposit on the seed crystals at a growth zone temperature of at least 375° C. and at a reactor pressure at least 700 bar.    
   
   
       15 . The method of  claim 14  further comprising heating the nutrient zone to a temperature that is at least 5° C. different than the growth zone, and the step of transporting the supercritical fluid includes transporting by convection.  
   
   
       16 . The method of  claim 14  wherein the solvent fluid comprises a mineralizer.  
   
   
       17 . The method of  claim 14  wherein positioning the seed crystals further comprises suspending the seed crystals in the chamber.  
   
   
       18 . The method of  claim 14  wherein positioning the seed crystals further comprises suspending more than one hundred seed crystals in the chamber.  
   
   
       19 . The method of  claim 14  wherein said nutrient material comprises Cd 1-x Zn x Se y Te 1-y , where 0≦x,y≦1.  
   
   
       20 . The method of  claim 14  further comprising 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, O and S.