FREQUENCY-RESOLVED SPECTROSCOPY AND ITS APPLICATION TO LIFETIME STUDIES IN A-SI-H

We present a rigorous analysis of the frequency-resolved spectroscopy (FRS) technique and its application to lifetime studies in the geminate recombination regime. It is shown that the quadrature signal (QFRS) is given by the convolution of the distribution for the logarithm of lifetimes P'(log tau) and a symmetric, sharply peaked ''scanning function'', allowing for an interpretation of the signal with respect to P'(log tau). This approach reveals that in high quality samples of low defect density a fast radiative process at tau = 1 mu s contributes to recombination in addition to the well known peak centred at tau approximate to 2ms. The experimental results are difficult to reconcile with the generally accepted recombination model for a-Si:H.