The gallium−chalcogen heterocubanes [Cp*Ga(μ3-E)]4, E = S (1) and Se (2), and [Cp†Ga(μ3-Se)]4 (3) have been synthesized by dehalosilylation reactions between E(SiMe3)2 (E = S, Se) and RGaCl2, R = Cp* (C5Me5) and Cp† (C5Me4Et), and are characterized by elemental analyses, NMR spectroscopy, and mass spectrometry. The use of compounds 1 and 2 as single-source MOCVD precursors for the low-temperature growth of Ga2E3 films at 290−310 °C is described. The as-deposited films were amorphous; however, upon thermal annealing (500 °C) the films crystallized to the thermodynamic cubic phases, while the corresponding tellurium analog decomposed in the solid state at 220 °C forming a gallium-rich product.