Impact of a surface laser treatment on the dielectric strength of α-alumina

The impact of laser treatments on the dielectric strength of α-alumina is investigated. In order to induce low surface modifications to strong damages, different laser processing parameters (fluence, assisting gas and its pressure, and laser wavelength) are applied. The experimental results clearly show that the dielectric strength is not really affected by the laser induced surface modifications. Surface cracks are consequently not considered to be involved in the breakdown mechanism. If any relationship exists between mechanical and dielectric strengths of α-alumina, the assumption considering that the prebreakdown event is the propagation of a mechanical crack from the surface has to be reconsidered.