Phase relationships in the ternary Ga-Ni-Sb system

Undesirable chemical reactions between metal contacts and a semiconductor substrate may be prevented by selecting metallization layers which are in thermodynamic equilibrium with the substrate. In order to determine the reaction products resulting from the formation of the Ni–GaSb contact, phase equilibria in the Ga–Ni–Sb system have been established experimentally at 500, 600 and 900°C. For the compound semiconductor GaSb negligible solid solubility of Ni was measured both at 500 and 600°C. In an attempt to clarify the existence of the ternary e-phase in this system, a number of alloys with various compositions were prepared, equilibrated, and examined by XRD, EPMA, and optical microscopy. In addition, the variation of the lattice parameters of the e-phase was determined as a function of composition at 900°C; the results are discussed in terms of the filling of the different lattice positions of the hexagonal unit cell