LOCK-IN RATE-WINDOW THERMOMODULATION (THERMAL WAVE) AND PHOTOMODULATION SPECTROMETRY

The application of the rate-window concept, familiar from deep level transient spectroscopy, to thermomodulation and photomodulation problems via lock-in detection has been investigated. Theoretical analysis of the newly adapted technique to these problems is presented and experimental photopyroelectric and photomodulated optical reflectance results are discussed. The utilization of the lock-in analyzer as a signal transient filtering system and as a dual-gate boxcar integrator equivalent with transient thermal wave signals is examined. Optimal instrumental conditions for use with thermal and electron-hole plasma analysis methodologies are presented, and experimental results with aluminum foil, crystalline and ion-implanted Si illustrate the potential of this measurement methodology for nondestructive thermal and electronic spectrometric evaluation of condensed phases and electronic materials.