SPIN-DEPENDENT TRANSPORT AND RECOMBINATION IN A-SI-H

We report on a study of spin-dependent photoconductivity in undoped a-Si:H. Applying the microwave modulation technique we observe in addition to the two already known e-db and h resonances an unusually broad quenching signal (g congruent-to 2.008, DELTA-H(fwhm) = 210 G). We varied the defect density N(d) systematically by electron bombardment and light soaking and found a pronounced dependence of the signal intensity of this line on N(d). This behavior is consistent with an assignment to the recombination of exchange coupled e-h pairs which are localized in the band tails. We present first results obtained on pin structures which confirm the current ideas about carrier collection in these devices.