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1994
Journal Article
Titel
Investigation of plasma expansion in the PLD process by means of an electrical probe
Abstract
The technique of electrical probe measurements has been used as a tool for the investigation of the dynamic properties of ions in the plasma plume during the removal of material from from an Al203 target by XeCl excimer laser radiation. The arrival time of the ions and the time-averaged expansion velocity of the propagating plasma plume were measured for different processing parameters (composition and pressure of processing gas, geometry of the set-up for the probe measurements). The time-averaged expansion velocity shows a maximum of 9x10 high 3 ms high -1 (processing gas Xe) at 6 mm distance to the target, and 2.1x10 high 4 ms high -1 (Ar) at distances of 10-12 mm. In the range of distances used (5-45 mm) the time-averaged expansion velocity was increasing under vacuum and reached the value of 2.7x10 4 ms high -1. Ion densities up to 6.3x10 high 15 cm high -3 were estimated for XeCl laser processing. complementary measurements with a COdeep2 TEA laser gave an ion density of 1.5x10 h igh 16 cm high -3.