Elucidation of LiCl encapsulated Bridgman growth of AlSb crystal

Aluminum antimonide (AlSb) possessing an indirect bandgap of 1.6 eV at room temperature offers a good option as a room-temperature dual-carrier radiation detector. However, the growth of AlSb crystal suffers from high reactivity of Al, causing sticking problems and polycrystallinity. Our work demonstrates experimentally that LiCl fully encapsulated Bridgman growth of AlSb is possible from near-stoichiometric AlSb melt. This leads to avoiding the interaction between the pyrolysis Boron Nitride (pBN) crucible and the melt, drastically decreasing nucleation on the peripheral crucible. Additionally, optimizing the melt composition and growth parameters provided a full understanding of LiCl encapsulated Bridgman growth of AlSb. Adding a slight amount of extra Sb into the stoichiometric AlSb melt can reduce the surface tension of the melt and enhance the stability of LiCl encapsulation efficiency. Conversely, it can also raise the risk of constitutional supercooling and promotes macroscopic defect formation. Accordingly, an optimized process was employed to obtain inclusion-free AlSb crystals with large grains (over 5 × 5 mm²) and homogeneous stoichiometric composition.