Device for producing the growth of a semiconductor material

Abstract

This device for producing the growth of a semiconductor material, in particular of type II-VI, uses a melt of the said semiconductor placed in a sealed bulb under vacuum or under controlled atmosphere, the said bulb being subjected to a sufficient temperature gradient for first maintaining the melt in the liquid state, then causing its progressive crystallization from the surface towards the bottom. The said device further comprises an element ( 3 ) capable of floating on the surface of the said melt, and equipped with a substantially central bore ( 4 ), intended on the one hand for receiving a seed crystal ( 5 ) or for permitting the nucleation leading to the preparation of a seed crystal ( 5 ′), and also of supporting the said seed crystal ( 5, 5 ′) above the melt while maintaining it in contact with the said melt in order to permit the continued crystallization from the said seed crystal ( 5, 5 ′) by lowering the temperature gradient.

1 . Device for producing the growth of a semiconductor material, in particular of type II-VI, from a melt of the said semiconductor placed in a sealed bulb under vacuum or under controlled atmosphere, the said bulb being subjected to a sufficient temperature gradient for first maintaining the melt in the liquid state, then causing its progressive crystallization from the surface towards the bottom, wherein it further comprises an element capable of floating on the surface of the said melt, and equipped with a substantially central bore, intended on the one hand for receiving a seed crystal or for permitting the nucleation leading to the preparation of a seed crystal, and also of supporting the said seed crystal above the melt while maintaining it in contact with the said melt in order to permit the continued crystallization from the said seed crystal by lowering the temperature gradient. 
   
   
       2 . Device for producing the growth of a semiconductor material according to  claim 1 , wherein the bore of the floating element has a frustoconical shape, whereof the small base is directed downwards and terminates in the melt, and whereof the large base is directed upwards. 
   
   
       3 . Device for producing the growth of a semiconductor material according to  claim 1 , wherein a growth seed crystal, hence solid, is previously positioned in the central bore, placed so that it is in contact with the melt but without allowing it to be completely or almost completely immersed therein. 
   
   
       4 . Device for producing the growth of a semiconductor material according to  claim 1 , wherein the floating element is made from a chemically and thermally inert refractory material, selected from the group comprising silica, alumina, silicon carbide, aluminium nitride and carbon in all its forms. 
   
   
       5 . Device for producing the growth of a semiconductor material according to  claim 4 , wherein the floating element is made from graphite. 
   
   
       6 . Device for producing the growth of a semiconductor material according to  claim 5 , wherein the floating element is machined, in order to optimize the heat transfers. 
   
   
       7 . Device for producing the growth of a semiconductor material according to  claim 5 , wherein the floating element is made from pyrolytic graphite. 
   
   
       8 . Device for producing the growth of a semiconductor material according to  claim 5 , wherein the floating element is made partly from dense graphite and partly from sheet graphite. 
   
   
       9 . Device for producing the growth of a semiconductor material according to  claim 4 , wherein the floating element is made from graphite, coated after machining and particularly after preparing the bore, with silicon carbide or with a thin deposit of pyrolytic carbon. 
   
   
       10 . Device for producing the growth of a semiconductor material according to  claim 1 , wherein the floating element substantially occupies the whole upper surface of the melt, with the exception of the central bore, in order to minimize the effects of the heat radiation inherent in the temperature of the melt.