| It is always an attracting research field for the interaction between laser and matters. In the latest several decades, as the repaid development of laser technology, it has been used in various aspects of natural science, and greatly accelerated the research progress. In the other hand, the new phenomena and findings in the research process greatly promoted the development of laser technology. The interaction between laser and matters is used not only in natural science but also in paractical application, for example, laser machining,laser induced nuclear fusion,pulsed lased deposition,laser weapon and so on.For GaAs materials, it has many advantageous characteristics. For example, it has direct transition energy band and high opoto-electro conversion efficiency so that it is used to fabricate solar cell.It can be made into high-speed device for its high electron mobility. It has high anti-radiation ability for its wide bandgap. Also for its special electron-transition effect, it is used to fabricate many new function devices etc. Thus GaAs materials find broad applications and become the second most inportant semiconductors after Si. Therefore, it is needed to study GaAs materials in detail, and laser-induced damage is one of the most important aspects.In this paper, a 532nm CW laser and a 1064nm pulsed-laser were used to study the interaction process between laser and GaAs materials. The novelty laser diffraction and interference methods were used to monitor the damage process of the samples. The damage threshold under CW and pulsed-laser were tested. An electronic probe microanalyzer was used to analyze the surface morphology and element changes of the damage materials, under which the damage forms of GaAs were dicussed qualitalively. On the basis of the experiments, a common heat conduction equation was used to calculate the damage threshold of the materials. And then, we summarized the damage mechanism, damage form of GaAs and relative theory model. The main contents were listed as follows:1. For the first time, a fraunhofer diffraction method was used to test the interaction process between 532nm CW laser and GaAs materials, and the damage threshold was tested accurately. From the analysis of the damage morphology and element change of the material surface with an electronic probe microanalyzer, we found that GaAs would decompound under high temperature, As vaporized from the surface, Ga and its oxid left behind.2. The theoretical damage threshold was calculated with a three-dimension heat conduction equation, and was in good accord with the experimental value. Both the experiments and the theory calculation proved the important influences of the surface defects on the damage threshold of GaAs.3. For the first time, the interaction process between GaAs and 1064nm pulsed-laser was studied with a interference method based on Mach-Zehnder interferometer, and the damage thereshold under single and multi-pulse laser was measured.4. The damage morphology of the GaAs surface was observed by an electronic probe microanalyzer.We found that the small defects of material surface had big influence on the damage form and damage threshold. The damage process of the sample with many defects would decompound and go with material removel, and the sample with less defects just melted down and damaged. The theoretical damage threshold was calculated with the one-dimension heat conduction equation.5. We summarized the interaction mechanism between fs ultra-short pulsed laser and GaAs.The ultra-fast interaction process went with the phenomena that the surface reflected second-harmonic signal would drop and the surface reflectivity would rise just after the ultra-short pulse duration. It is commonly accepted that the symmetry change of the thin surface layer accounted for the drop of the second-harmonic reflection, while the ultra-non-equilibrium between the electron system and lattice because of the powerful electric field and ultrashort interaction time of the fs laser leaded to the reflectivity rise. |
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