Published online by Cambridge University Press: 26 February 2011
The thermodynamic interrelation between the amorphous semiconducting (a-sc), the diamond cubic (c-sc) and the liquid metal (lm) states of Ge and Si is reviewed with especial emphasis on the question of the thermodynamic uniqueness of the a-sc state following its structural relaxation. The experience on the occurrence of the direct lm→a-sc transition and its reverse is surveyed and interpreted. This experience, in conjunction with the lm undercooling studies of Devaud and the author, indicates that the formation, in the metastable regime, of a-sc from lm results from preferential growth rather than preferential nucleation.