Phase controlled synthesis and optical properties of ZnS thin films by pulsed laser deposition

Both zinc-blende and wurtzite ZnS thin films have been successfully synthesized on uncoated and Au-coated sapphire substrates by pulsed laser deposition (PLD). Structure phase transitions from zinc-blende phase to the mixture of zinc-blende and wurtzite have been observed with increasing temperature from room temperature to 500 °C for the ZnS thin films deposited on uncoated sapphire substrate, while only the wurtzite phase has been identified for the ZnS thin films deposited on Au-coated sapphire substrate. The SEM images show that the ZnS thin film deposited on Au-coated sapphire substrate has a high crystallinity over that of uncoated sapphire substrate. For all the prepared samples room-temperature photoluminescence (PL) measurements with a 325 nm excitation show two emission bands at ∼405 nm and ∼520 nm, respectively.