Stabilizing laser energy density on a target during pulsed laser deposition of thin films

摘要

A process for stabilizing laser energy density on a target surface during pulsed laser deposition of thin films controls the focused laser spot on the target. The process involves imaging an image-aperture positioned in the beamline. This eliminates changes in the beam dimensions of the laser. A continuously variable attenuator located in between the output of the laser and the imaged image-aperture adjusts the energy to a desired level by running the laser in a “constant voltage” mode. The process provides reproducibility and controllability for deposition of electronic thin films by pulsed laser deposition.

主权项

1. A process for stabilizing laser energy density on a target during pulsed laser deposition, comprising:
generating laser beam pulses of ultraviolet light from a laser; and thereafter directing the laser beam pulses to an image-aperture that allows passage of a chosen central portion of the laser beam through the image-aperture while preventing passage of an outer portion of the laser beam through the image-aperture; and thereafter directing the laser beam pulses from the image-aperture to a lens having a focal length, the lens producing a de-magnified image of the image-aperture on a target inside a deposition chamber according to an equation1f=1si+1so,wherein f is a value for the focal length of the lens, wherein si is a value for a distance from the lens to the image of the laser beam on the target, and wherein so is a value for a distance from the image-aperture to the lens; and thereafter
directing the laser beam pulses from the lens to the target in the deposition chamber, thereby stabilizing the laser energy density on the target, the laser beam pulses ablating material from the target; and thereafter depositing a film onto the substrate from ablated material from the target.