Enhanced photoconductivity in thin-film semiconductors optically coupled to photonic crystals.

摘要

The photoconductivity of a thin semiconductor film is enhanced by depositing a photonic crystal (PC) onto its backside. The greatest photoconductivity enhancement is achieved when the thickness of the film is such that a resonant state appears within the stop-gap of the PC. Specifically, the photoconductivity of a 96nm thick hydrogenated amorphous silicon film is increased by 60% by depositing an opaline PC onto the backside of this film. However, increasing the thickness of the film to 110nm causes a resonant state to appear within the stop-gap of the PC, and in this case the photoconductivity is enhanced by another 70%. Notably, the semiconductor film itself does not need to be periodically structured to exhibit enhanced photoconductivity, allowing the simple architecture of the film-PC construct to be readily applied to a variety of devices including resonant cavity enhanced photodiodes and more efficient photovoltaics.