Time-resolved spectroscopy of non-thermal carrier dynamics in GaN

• Published in: Current applied physics pp. 909 - 912
• Main Authors: K. Kyhm, R. Lota, R.A. Taylor, J.F. Ryan, N.J. Cain
• Format: Journal Article
• Language: Korean
• Published: 한국물리학회 01-09-2006
• Subjects: 물리학
• ISSN: 1567-1739; 1878-1675

The dynamics of carriers in GaN epilayers is investigated using femtosecond pump-probe spectroscopy. After the residual chirpon the continuum probe is removed, the normalized dierence spectra (NDS) for dierent probe energies are synchronized, recov-ering the full time resolution of our laser pulse. Our Monte-Carlo simulation agrees well with the unchirped NDS spectrum, whichshows the development of the carrier distribution at early times, where phonon satellites are seen, together with a strong non-ther-mal electron distribution in the region of the LO-phonon energy arising from the remarkably strong electronLO phonon interac-tion. Employing a new technique which involves the integration of the normalized NDS multiplied by the corresponding energy, ameasure of the mean energy of the carriers in non-thermal states is obtained. By comparing the time-dependent energy loss with thetheoretical energy loss rate, we estimate the eective temperature of the phonon modes as well as the population of phonons. KCI Citation Count: 3