InGaAs single crystal using a GaAs seed grown with the vertical gradient freeze technique

Abstract We have succeeded in growing the InGaAs single crystal using a GaAs seed with the vertical gradient freeze technique (VGF) with good reproducibility. The orientation of the GaAs seed is (0 0 1). The boundary conditions between the GaAs seed and the InGaAs VGF crystal, the shape of the solid–liquid interface during crystal growth, and the growth mode of the crystal have been studied as basic conditions for the single crystal growth. We found that (1) The polycrystallinity due to the lattice mismatch between the GaAs seed and the InGaAs VGF crystal can be suppressed when the composition difference Δ x between the GaAs seed and the InGaAs crystal is less than 0.05. (2) It is possible to make the solid–liquid interface convex toward the melt by reducing the temperature gradient of the growth zone, which prevents other grains occurring near the crucible wall from propagating to the crystal center region. (3) A normal freezing growth mode can be attained by reducing the lowering rate of the furnace temperature, which prevents compositionally abnormal regions from occurring during crystal growth. The InGaAs crystal obtained is 15 mm long and consists of a single crystal region. The diameter of the growth region is 15 mm, which is the same as that of the GaAs seed. The maximum InAs composition is 0.34