Laser Excited Electronic and Thermal Elastic Vibrations in a Semiconductor Rectangular Plate

International audiencePhotoacoustic (PA) and photothermal (PT) effects can be important as driven mechanisms for micromechanical structures, especially for micro-(opto)electro-mechanical structures (MOEMS). A new approach for producing compact, lightweight, a highly sensitive detector is provided by MOEMS technology, which are based on the the elastic bending of microstructure generated by absorption of modulated optical power. The electronic and thermal elastic vibrations (the electronic deformation and thermoelastic mechanisms of elastic wave generation) in a semiconductor rectangular simply supported plate (3D geometry), photogenerated by a focused and intensity-modulated laser beam, were studied. The theoretical model for the elastic displacements space and frequency distribution by using the Green function method was given. The amplitude of the elastic bending in the rectangular plate were calculated and analysed, including the thermalization and surface and volume recombination heat sources. The theoretical results were compared with the experimental data. These investigations are important for many practical experimental situation (atomic force microscopy, thermal microscopy, thermoelastic microscopy, etc) and sensors and actuators