Group iii element nitride crystal producing method and group-iii element nitride crystal

Abstract

A method for producing a high-quality group-III element nitride crystal at a high crystal growth rate, and a group-III element nitride crystal are provided. The method includes the steps of placing a group-III element, an alkali metal, and a seed crystal of group-III element nitride in a crystal growth vessel, pressurizing and heating the crystal growth vessel in an atmosphere of nitrogen-containing gas, and causing the group-III element and nitrogen to react with each other in a melt of the group-III element, the alkali metal and the nitrogen so that a group-III element nitride crystal is grown using the seed crystal as a nucleus. A hydrocarbon having a boiling point higher than the melting point of the alkali metal is added before the pressurization and heating of the crystal growth vessel.

1 - 12 . (canceled) 
     
     
         13 . A group-III element nitride crystal comprising at least one dopant selected from the group consisting of Si, O, Ge, Sn, Mg, Sr, Ea, Zn and Ca, the group-III element nitride crystal having an optical absorption coefficient of 10 cm −1  or less with respect to light having a wavelength of 400 nm or more and 620 nm or less. 
     
     
         14 . The group-III element nitride crystal according to  claim 13 , wherein
 the group-III element is at least one element selected from AI, Ga and In, and   the group-III element nitride is a compound represented by AlsGatln (1-s-t) N, where 0≦s≦1, 0≦t≦1, and s+t≦1.   
     
     
         15 . The group-III element nitride crystal according to  claim 14 , wherein
 the group-III element is Ga, and   the group-III element nitride is GaN.   
     
     
         16 . A substrate for forming a semiconductor device including a group-III element nitride crystal, wherein
 the group-III element nitride crystal is the group-III element nitride crystal according to  claim 13 .   
     
     
         17 . A semiconductor device, wherein
 a semiconductor layer is formed on a substrate, and   the substrate is the substrate according to  claim 16 .   
     
     
         18 . The group-III element nitride crystal according to  claim 13 , wherein content of the dopant is 1×10 15  cm −3  or more. 
     
     
         19 . The group-III element nitride crystal according to  claim 13 , wherein content of the dopant is 1×10 19  cm −3  or less. 
     
     
         20 . A group-III element nitride crystal, having an optical absorption coefficient of 10 cm −1  or less with respect to light having a wavelength of 400 nm or more and 620 nm or less, and having an EPD density of 5×10 5  (cm −2 ) or less. 
     
     
         21 . The group-III element nitride crystal according to  claim 20 , wherein
 the group-III element is at least one element selected from AI, Ga and In, and   the group-III element nitride is a compound represented by AlsGatln (1-s-t) N, where 0≦s≦1, 0≦t≦1, and s+t≦1.   
     
     
         22 . The group-III element nitride crystal according to  claim 21 , wherein
 the group-III element is Ga, and   the group-III element nitride is GaN.   
     
     
         23 . The group-III element nitride crystal according to  claim 20 , having an EPD density of 1×10 4  (cm −2 ) or more. 
     
     
         24 . A substrate for forming a semiconductor device comprising the group-III element nitride crystal of  claim 20 . 
     
     
         25 . A semiconductor device comprising the substrate of  claim 24  and a semiconductor layer formed on the substrate.