engleski

Spectroscopy of GaAs laser produced plasma

We have studied the emission from laser produced plasma of GaAs depending on helium and argon background pressure. We used nanosecond Nd:YAG pulsed laser at 1064 nm to ablate GaAs (100) rotated target. The laser fluence was 28 J/cm2. The gas pressure was changed in the range from 5∙10-3 to 150 mbar. Characteristic spectral lines of As I, II, III and Ga I, II were chosen to monitor time evolution of the plasma plume content. Spectral selection was achieved by means of 60 cm monochromator equipped with a photomultiplier. Spatial selection of the upper part of the plume was achieved by use of an optical imaging system that projects narrow part of the plume onto the entrance slit. A time resolved signals were recorded by means of a digital oscilloscope. These signals show different (de)excitation mechanisms for different atomic states. Simultaneously images of the plasma plume shape at given pressure were recorded by commercial CCD camera. We have found that ratios of neutrals and ions emission intensities depend on background gas pressure. Results for argon and helium are compared and discussed in terms of possible application to pulse laser deposition technique.

Pulsed laser deposition; GaAs

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