A disclination model for the twin-twin intersection and the formation of diamond-hexagonal silicon and germanium

A twin-twin intersection mechanism for twinning in semiconductors is presented. The mechanism is based on the disclination character of twins and accounts for all experimental findings including the diamond-hexagonal structure, the twin/matrix orientation relationship, and the shape of the intersected volume, as well as irregularities within the transformed region such as stacking faults and diamond cubic bands. The formation of long narrow diamond-hexagonal bands is proposed to be due to a similar mechanism where a second-order twin penetrates into the matrix.