摘要
A noncontact photoacoustic technique using air transducers in MHz range is presented.Firstly, theoretical simulation and experimental fabrication of ultrasonic transducers in airare considered. An improvement of about 50 dB in the round-trip insertion loss and a frac-tional bandwidth greater than 15% are obtained by using one or two matching layers. Then,the 1 MHz photoacoustic measurement system is described and different applications are dis-cussed. The phase shifts of the received acoustic waves are extracted to obtain the surfacetopography of samples. The ion implantation dose in semiconductor is measured by detectingthe photoacoustic signal in air. Finally, a photoacoustic method for quantitative determina-tion of thin-film thicknesses is proposed.
A noncontact photoacoustic technique using air transducers in MHz range is presented.Firstly, theoretical simulation and experimental fabrication of ultrasonic transducers in airare considered. An improvement of about 50 dB in the round-trip insertion loss and a frac-tional bandwidth greater than 15% are obtained by using one or two matching layers. Then,the 1 MHz photoacoustic measurement system is described and different applications are dis-cussed. The phase shifts of the received acoustic waves are extracted to obtain the surfacetopography of samples. The ion implantation dose in semiconductor is measured by detectingthe photoacoustic signal in air. Finally, a photoacoustic method for quantitative determina-tion of thin-film thicknesses is proposed.
基金
Project supported by the National Foundation of China for post-doctoral researches.
