Synthesis and structural characterization of microcrystalline Ga2S3 layers on a GaP semiconductor substrate

Gallium sulfide (Ga2S3) belongs to a group of wide bandgap semiconductors with interesting properties for infrared and nonlinear optics applications. Recent interest in Ga2S3 material focuses on the passivation of various semiconductor surfaces to enhance their electrical and optical properties. This work concerns the growth of microcrystalline gallium sulfide layers on semiconductive GaP substrates. The Ga2S3 layers were successfully obtained by reacting sulfur vapour with thin GaP semiconductor plates at two different temperatures: 450 degrees C and 600 degrees C. At the lower temperature (400 degrees C), no gallium sulfide layer formation was observed on the GaP substrate. Atomic force microscopy and Scanning Electron Microscopy were applied to illustrate the topography of the obtained Ga2S3 layers. Their thickness ranged from a few hundred nanometers to about 1-2 mu m. The synthesized layers were structurally characterized by Raman spectroscopy. Raman polarization measurements were used to determine the crystalline phase of the Ga2S3 films. Raman tensor coefficients were obtained by fitting the most intensive Ga2S3 peaks to experimental data. The symmetry of the Raman peaks was in good agreement with the monoclinic Ga2S3 crystal phase.