Semiconductor device and method of manufacture thereof

Abstract

A structure including a substrate, an intermediate layer provided and formed directly onto the substrate, a transition region, and a group II-VI bulk crystal material provided and formed as an extension of the transition region. The transition region acts to change the structure from the underlying substrate to that of the bulk crystal. In a method of manufacture, a similar technique can be used for growing the transition region and the bulk crystal layer.

1 . A structure including a substrate, an interfacial layer provided and formed directly onto the substrate, a transition region, and a group II-VI bulk crystal material provided and formed as an extension of the transition region. 
     
     
         2 . A structure according to  claim 1 , in which the substrate comprises a substrate of silicon, gallium arsenide, germanium, or silicon carbide. 
     
     
         3 . A structure according to  claim 1 , in which the substrate has a thickness of at least 100 microns, preferably at least 200 microns. 
     
     
         4 . A structure according to  claim 1 , in which the substrate has a diameter greater than 25 mm. 
     
     
         5 . A structure according to  claim 1 , in which the bulk crystal material comprises cadmium telluride, cadmium zinc telluride, or cadmium manganese telluride. 
     
     
         6 . A structure according to  claim 1 , in which the bulk crystal material has a thickness of at least 700 microns. 
     
     
         7 . A structure according to  claim 1 , in which the intermediate layer comprises or group II-VI material such as CdTe, CZT, CdS. 
     
     
         8 . A structure according to  claim 1 , in which the intermediate layer has a thickness of between 25 and 1000 microns. 
     
     
         9 . A structure according to  claim 1 , in which the transition region between the intermediate layer to the material of the bulk crystal has a thickness of between 10 and 500 microns. 
     
     
         10 . A method of forming a structure according to  claim 1 , in which the interfacial region and the bulk crystal are deposited using the same growth technique, using a variation in the growth parameters during the growth cycle to form the interfacial region and the bulk crystal. 
     
     
         11 . A method of growing a bulk single crystal material comprising:
 providing a seed substrate of a material different from the bulk crystal material to be formed;   forming an intermediate layer on the substrate;   forming a transition region on the intermediate layer; and   forming the bulk single crystal material is grown on the transition region using a physical vapour phase deposition method.   
     
     
         12 . The method according to  claim 11 , in which the intermediate layer is formed using standard thin film deposition techniques. 
     
     
         13 . The method according to  claim 12 , in which the intermediate layer is formed using molecular beam epitaxy, chemical vapour deposition, sputtering, metal organic vapour phase epitaxy, liquid phase epitaxy and metallo organic chemical vapour deposition (MOCVD). 
     
     
         14 . The method according to  claim 11 , in which the intermediate layer is formed using physical vapour phase deposition techniques. 
     
     
         15 . The method according to  claim 14 , in which the intermediate layer or region is grown at a growth rate of between 1 and 10 microns/hour. 
     
     
         16 . The method according to  claim 11 , in which the transition region is formed using the same growth technique as used for the subsequent deposition of the bulk crystal material, but with a variation in the growth parameters during the growth cycle to gradually accelerate the rate of growth. 
     
     
         17 . The method of  claim 16 , in which the intermediate layer is formed using the same growth technique as used for the subsequent deposition of the bulk crystal material, but with a variation in the growth parameters during the growth cycle to gradually accelerate the rate of growth. 
     
     
         18 . The method according to  claim 16 , in which the growth parameters that are varied include one of the source temperature (T source ) and the substrate temperature (T sub ). 
     
     
         19 . The method according to  claim 18 , in which the temperature differential between the substrate temperature and the source temperature is increased to increase the growth rate. 
     
     
         20 . The method according to  claim 16 , in which the variation in the growth parameter is a gradual variation. 
     
     
         21 . The method according to  claim 16 , in which the variation in the growth parameter is an abrupt variation. 
     
     
         22 . The method according to  claim 11 , in which the source temperature is at least 450° C. 
     
     
         23 . The method according to  claim 11 , in which the substrate temperature is at least around 200° C. 
     
     
         24 . The method according to  claim 11 , in which the substrate is a silicon or gallium arsenide substrate. 
     
     
         25 . The method according to  claim 11 , in which the substrate has a diameter greater than about 25 mm. 
     
     
         26 . The method according to  claim 25 , in which the substrate has a diameter of at least 50 mm, and most preferably at least 150 mm. 
     
     
         27 . The method according to  claim 11 , in which the bulk crystal material comprises one of zinc telluride, cadmium telluride, cadmium zinc telluride and cadmium manganese telluride. 
     
     
         28 . The method according to  claim 27 , in which the bulk crystal material has the composition Cd 1-x Zn x Te or Cd 1-x Mn x Te. 
     
     
         29 . The method according to  claim 11 , in which the bulk crystal material is grown at a growth rate of between 100 and 500 microns/hour. 
     
     
         30 . The method according to  claim 11 , in which the bulk crystal material has a thickness of at least 500 microns. 
     
     
         31 . The method according to  claim 11 , in which the substrate and crystal material grown on the substrate are divided into smaller pieces after formation. 
     
     
         32 . The method according to  claim 11 , further comprising the step of forming an x-ray or gamma ray detector. 
     
     
         33 . The method according to  claim 11 , in which the bulk crystal may itself be used as a seed crystal for the formation of other bulk crystal materials in accordance with the method of any one of the preceding claims.