FULL ENCAPSULATION BY MOLTEN-SALTS DURING THE BRIDGMAN GROWTH-PROCESS

Full encapsulation of liquid semiconductors during Bridgman growth hel ps to improve the crystal quality by decreasing the nucleation of grai ns and the dislocation density. An experimental and theoretical study has been undertaken in order to better understand the phenomena and to determine the necessary conditions to be achieved. In the case of the LiCl-KCl encapsulant in silica crucibles, surface energy calculations predict a stable salt layer between the molten semiconductor and the crucible. For GaAs growth with B2O3 encapsulant, surface energies are not strong enough and it is shown that the oxide layer is due to the h igh viscosity of the encapsulant which prevents it flowing upward. It is then mandatory to have a good wetting of the crucible walls by the baron oxide before the melting of the semiconductor.