Pulsed Laser Deposition (PLD)

I acted as “tool owner” for this Pulsed Laser Deposition (PLD) system during my masters and PhD, managing modifications, maintenance, operation, and training new users. This is a KrF excimer laser (Lambda Physik model Compex 201, Germany) with incident wavelength 248 nm, and energy density of ~40 J/cm2. The chamber on the end is a cryo-pumped ultra-high vacuum system with base pressure <10^-9 Torr and substrate temperature up to 850 C.

PLD is an excellent technique to deposit thin films of complex structured materials such as the high-temperature superconductor YBCO. The technique works using high powered focused laser pulses to ablate material from a target, forming a plasma plume that condenses onto the substrate. Because of the very high energy density of the incident laser, multi-element targets with widely varying masses and sputter yield are all vaporized at the same rate. The laser energy can be tuned to deposit a single monolayer or less per pulse, allowing precise thickness control and deposition rate. This leaves only the kinetic decomposition and desorption on the sample surface as the dominant barrier to the stoichiometric deposition of high vapor pressure materials. Additionally, PLD can be performed under a wide range of gaseous environments, from UHV conditions to very high pressures.