(The) electrical and optical properties of Erbium-doped hydrogenated amorphous silicon

Abstract

Great interest lies in hydrogenated amorphous silicon (α-Si:H) as the host matrix for erbium-doped silicon-based semiconductor. But so far, preparation methods used have made it difficult to produce erbium-doped α-Si:H films with the good electrical quality. Here we report on the electrical and optical properties of hydrogenated amorphous silicon deposited and doped with erbium by using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) of silane with concurrent sputtering of erbium. A-Si:H without erbium shows photosensitivity greater than $10^5$, demonstrating the good electrical quality. Doping with erbium increases the room temperature conductivity by $10^3$. The activation energy for conductivity also changes from 0.9eV to 0.5eV. Taken together, the data indicate that erbium works as an active dopant. And room temperature photoluminescence at 1.54㎛, due to an intra-4f transition in $Er^{3+}$, is observed. Excitation of $Er^{3+}$ is shown to be mediated by photocarriers.