Study on the twinning in LEC-GaSb crystals

Abstract

Twinning is a critical factor limiting the size and yield of III-V semiconductor single crystals. In this work, the < 100 > GaSb crystals were grown by the liquid-encapsulated Czochralski (LEC) method, and the influences of dislocations and {111} facets on twinning were studied. During the seeding and shouldering, the low-angle grain boundaries resulting from dislocation multiplication typically induce twinning or polycrystallization. Moreover, when growing < 100 > GaSb crystals, twinning tends to occur preferentially on the ($\overline{\text{1}}\overline{\text{1}}\overline{\text{1}}$)Sb plane. First-principles calculations revealed that the stacking fault energy (SFE) of the ($\overline{\text{1}}\overline{\text{1}}\overline{\text{1}}$)Sb plane (25.36 mJ/m²) is much smaller than that of the (111)Ga plane (54.25 mJ/m²), indicating a higher propensity for twin nucleation on the ($\overline{\text{1}}\overline{\text{1}}\overline{\text{1}}$)Sb plane, thereby confirming the experimental observations. The experimental results show that at the solid–liquid growth interface, the supercooling(ΔT) near the ($\overline{\text{1}}\overline{\text{1}}\overline{\text{1}}$)Sb plane is significantly higher than on the (111)Ga plane, which leads to a considerably greater probability of twinning nucleation occurring on the ($\overline{\text{1}}\overline{\text{1}}\overline{\text{1}}$)Sb plane. The abrupt increase in ΔT caused by local temperature fluctuations may be the primary reason for twinning in < 100 > GaSb crystals.