RECOMBINATION IN A-SI-H FILMS AND PIN-STRUCTURES STUDIED BY ELECTRICALLY DETECTED MAGNETIC-RESONANCE (EDMR)

Spin-dependent recombination in a-Si:H has been studied by electricall y detected magnetic resonance (EDMR). The spectra are dominated by the electron-dangling bond resonance which arises from tunnelling transit ions of electrons localized in the bandtail into neutral dangling bond s. In undoped films the resonant decrease of the photoconductivity Del ta sigma/sigma varies in the range 10(-5)-10(-2), depending on the def ect density. It is shown that this magnitude is consistent with the as sumption that this tunnelling transition is the dominating recombinati on step. In pin-structures the shape of the spectra and the sign (enha ncing or quenching) depend on the operational conditions of the device (bias, illumination). The results suggest that the transport in the d ark and the charge collection under illumination are controlled by rec ombination in the bulk of the i-layer. Degradation of the device occur s primarily by an enhancement of the recombination in the bulk of the i-layer.