THE MEASUREMENT OF THE TEMPERATURE INSIDE THE HOT PHONON SPOT INDUCEDBY LASER EXCITATION OF SILICON

The heat pulses produced by laser excitation were measured in Si using YBCO sensor. The observed pulse shapes confirm the existence of the p honon hot spot in certain experimental conditions. The exploiting of Y BCO bolometer and rather thin Si sample allowed the direct measurement of the hot spot temperature and its life time. Measured hot spot para meters are in satisfactory agreement with those obtained by help of Ka zakovtsev-Levinson theory. The Monte-Carlo simulation of phonon propag ation was carried out with account of coalescence process. It was foun d that with increase of excitation energy density, the calculated resp onse peak position shifts noticeably to greater time values.