Pulsed Laser Deposition (PLD) System - diagram

Pulsed laser deposition (PLD) is widely used in the materials processing industry. With this technique, multi-component materials can be ablated from the the target and deposited onto a substrate to form stoichiometric layers which match the target material. A basic PLD system has been set up at Colorado State University. Figures show a schematic diagram of the CSU system. A krypton fluoride (KrF) excimer laser with a wavelength of 248 nm (Lambda Physik model LPX 305 i) is used as the energy source. The maximum output energy of the laser is about 1200 mJ per pulse at a pulse duration of 25 ns. The maximum repetition rate is 50 Hz. The laser beam is focused into a rotating target stage and it is rastered using a stepper motor driven mirror. The target angle of incidence is 45 degrees. The laser spot size on the target surface is about 0.1 mm². A mechanical rotary pump (HyVac 55L) and a turbomolecular pump (Electrorava ) are used to evacuate the vacuum chamber. The chamber can be pumped down to a base pressure of 2.5 X 10^-7 Torr. A baratron (MKS 127A) and ionization gauge are used to detect the pressure of the chamber in a range 10^{-3 -} 10^-7 Torr. The oxygen pressure in chamber is controlled with an MKS 651C pressure controller and an MKS 247C four-channel readout. The substrate heater (Blue Wave Semiconductor) can be operated from high vacuum (10^-7 Torr) up to an oxygen pressure of 1 atmosphere. The maximum temperature of operation in vacuum or in an oxygen atmosphere is 900 ^oC. The substrate heater can be used at temperatures up to 950 ^oC for short periods (up to 30 min).