| 摘要 |
PURPOSE:To strictly fix the width of the molten zone and to obtain the title GaAs single crystal wherein the change in the dopant concn. in the longitudinal direction of the crystal is minimized by forming a temp. distribution having two peaks in a high-temp. furnace and adjusting the respective peak temps. at the two solid-liq. interface. CONSTITUTION:A high-temp. furnace is provided on the boat 2 side of the position of a capillary 8 in an ampule 1, and a low-temp. furnace is furnished on the As 6 side. The temp. distribution TH is initially set at such a temp as to melt the entire GaAs crystal in the boat 2 except a seed crystal 3 in the boat 2. A temp. distribution TB having the two peak temp. TP1 and TP2 close to each other is formed at the position of the seed crystal 3. The ampule 1 or a ZM device is then moved to move the soln. 7 from the seed crystal 3 to the rear end of the boat 2, and a GaAs single crystal 4 is formed. The peak temp. TP1 of the temp. distribution TB on the seed crystal 3 side is gradually elevated after seeding, the peak temp. TP2 is gradually lowered, and a melt zone having a constant width X is formed at a fixed position.
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