| 摘要 |
PURPOSE:To form a titled single crystal having small dislocation density and a large diameter (>= about 2 inches) by pulling a GaAs molten liquid which is doped with a specified amt. of In under prescribed pulling conditions in manufacturing the GaAs single crystal with the LEC method. CONSTITUTION:When undoped (not added) GaAs is formed by the LEC method (liquid-sealed Czochralski method), the pulling of a single crystal is carried out under conditions such as to obtain the GaAs single crystal having <=15,000cm<-2> dislocation density (outer circumferential part is excluded). Namely a GaAs molten liquid, which is added with In so that the In concn. in the crystal may be regulated to 1,200-2,800wt.ppm is pulled under said conditions to manufacture a GaAs single crystal having <=1,000cm<-2> dislocation density. For example, an undoped crystal C having 8,000-14,000 dislocation density can be obtained under conditions shown by the table I . However, when the In concn. in the crystal is regulated to 1,600wt.ppm under said conditions (the temp. gradient in B2O3: 60 deg.Ccm<-1>). A low-dislocation density GaAs single crystal A having 400- 600 dislocation density is obtained. |
