Growth of GaS on GaAs(100)-(4×2) with the single-source precursor [(tBu)GaS]4

The growth of a GaS film on the GaAs(100)-(4×2) surface, using [(tBu)GaS]4, has been studied in ultra-high vacuum using high-resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and temperature-programmed desorption (TPD). Upon the adsorption of a monolayer of GaS, we observed the formation of a (2×1) superstructure, as evidenced by LEED. For multilayer growth at 650 K, a (1×1) LEED pattern was observed. For submonolayer coverages of the precursor adsorbed at 100 K, thermally induced β-hydrogen elimination of the tert-butyl ligands was observed at 650 K, as evidenced by concurrent desorption of isobutene and molecular hydrogen. An amorphous GaS film is formed after multilayer adsorption of [(tBu)GaS]4 at 100 K, followed by annealing to 650 K. However, isobutane, isobutene, and molecular hydrogen desorption is seen from such a surface, suggesting an additional tert-butyl ligand removal pathway. Finally, layer-by-layer growth of a GaS film was achieved by a cyclic process of monolayer adsorption of [(tBu)GaS]4 at 200 K, followed by annealing to 700 K.