CRYSTAL AND SUBSTRATE OF CONDUCTIVE GaAs, AND METHOD FOR FORMING THE SAME

Abstract

An electrically conductive GaAs crystal has an atomic concentration of Si more than 1×10 17 cm −3 , wherein density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm −2 . In this case, it is preferable that the conductive GaAs crystal has a dislocation density of at most 2×10 −2 cm 2 or at least 1×10 −3 cm 2 .

1 . A conductive GaAs crystal having an atomic concentration of Si more than 1×10 17  cm −3 , wherein a density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm −2 . 
     
     
         2 . The conductive GaAs crystal according to  claim 1  having a dislocation density of at most 5×10 2  cm −2  or at least 1×10 3  cm −2 . 
     
     
         3 . The conductive GaAs crystal according to  claim 1 , which have been grown and then annealed at a temperature of at least 1130° C. for at least 10 hours in a crystal growth furnace. 
     
     
         4 . A conductive GaAs crystal substrate cut from the conductive GaAs crystal of  claim 1  and having a polished mirror surface. 
     
     
         5 . The conductive GaAs crystal substrate according to  claim 4 , wherein in said mirror surface a density of microscopic defects having sizes of at least 0.265 μm measured by a surface particle inspection devise is at most 0.5/cm 2 . 
     
     
         6 . A method for producing the conductive GaAs crystal of  claim 1 , wherein said conductive GaAs crystal is grown and thereafter annealed at a temperature of at least 1130° C. for at least 10 hours.