Method of producing GaAs single crystal and GaAs single crystal wafer
A method of producing a GaAs single crystal having high carrier concentration and high crystallinity and to provide a GaAs single crystal wafer using such a GaAs single crystal. In the method of producing a GaAs single crystal, a vertical boat method is performed with a crucible receiving a seed crystal, a Si material, a GaAs material serving as an impurity, solid silicon dioxide, and a boron oxide material, thereby growing a GaAs single crystal.
1. A method of producing a GaAs single crystal, wherein a vertical boat method is performed with a crucible storing a seed crystal, a Si material serving as an impurity, a GaAs material, a solid silicon dioxide, and a boron oxide material in which SiO 2 is previously added into the boron oxide material, thereby growing a GaAs single crystal,
wherein the solid silicon dioxide is in a disk shape and is provided between the GaAs material and the boron oxide material,
a ratio of an area of the solid silicon dioxide to an area of the upper surface of the GaAs material at a start of crystal growth is 90% to 99%,
an amount of Si of SiO 2 previously added into the boron oxide material is 5 mass % or less, and
a sum of an amount of Si of SiO 2 in the boron oxide material and an amount of Si in the solid silicon dioxide exceeds 5 mass % of the boron oxide material.
2. The method of producing a GaAs single crystal according to claim 1 , wherein in a specific period in the growth of the GaAs single crystal, liquid boron oxide which is a melt of the boron oxide material is stirred.
3. A Si-doped GaAs single crystal wafer, wherein a carrier concentration is higher than 2×10 18 cm −3 , the maximum value of an etch pit density is 500 cm −2 or less, the B concentration is in a range of 1.9×10 18 cm −3 to 6.0×10 18 cm −3 , and the Si concentration is in a range of 4.3×10 18 cm −3 to 6.2×10 18 cm −3 .
4. The method of producing a GaAs single crystal according to claim 1 , wherein in a specific period in the growth of the GaAs single crystal, liquid boron oxide which is a melt of the boron oxide material is stirred.
5. The Si-doped GaAs single crystal wafer according to claim 3 , wherein a carrier concentration is 2×10 18 cm −3 to3.1×10 18 cm −3 .
6. The Si-doped GaAs single crystal wafer according to claim 3 , wherein an average value of an etch pit density is 8 cm −2 to 21 cm −2 .
7. The Si-doped GaAs single crystal wafer according to claim 5 , wherein an average value of an etch pit density is 8 cm −2 to 21 cm −2 .