Properties of (Ge2) x (GaAs)1− x alloys grown by molecular beam epitaxy

Single-crystalline (Ge2)x(GaAs)1−x alloys have been grown by molecular beam epitaxy on GaAs (100) substrates at substrate temperatures of 550 and 430 °C. The structure of these alloys has been studied using transmission electron microscopy. We observe that growths done at 550 °C show a compositional phase separation, within a structurally single-crystalline lattice, into Ge-rich and GaAs-rich domains whose sizes are of the order of 100 Å. Growths at 430 °C appear to be both single phase and single crystalline. Room-temperature Hall measurements on the single-phase alloys show them to be n type.