Light-induced effects in a-Si:H(Er)

While the luminescence of a-Si:H(Er) has been studied quite extensively there is no data on the light-induced effects in this material. The latter, however, are important for electroluminescent devices. We have investigated the light-induced metastable state in a-Si:H(Er) with the measurements of optical absorption in the below-gap region and dark conductivity before and after illumination of the films by band gap light. PECVD a-Si:H(Er) films prepared under various conditions have been studied. To elucidate the details concerning the peculiarities of light-induced phenomena in a-Si:H(Er) the obtained results have been compared with the data for a-Si:H(As) films with similar Fermi level position. We have found that after long illumination time the changes of electric properties of a-Si:H(Er) films were determined by dangling bond creation as in a-Si:H(As) film. For short illumination time the persistent photoconductivity was observed in a-Si:H(Er) films. A possible origin of this phenomenon is discussed from the viewpoint of structural disorder induced by erbium–oxygen complexes incorporation.