engleski

Nanostructured silicon for hybrid Si/organic devices

Micro- and nanostructured silicon surfaces are often used for performance enhancement in sensing devices, with performance enhancement scaling with increased surface area of structured silicon that is exposed for sensing, or with increased light absorbance due to the light-trapping effects of rough silicon surface. We present optoelectronic devices based on hybrid silicon-organic heterojunctions formed between micro- and nano-structured p-doped silicon surfaces obtained by electrochemical anodisation, metal-assisted chemical etching, anisotropic silicon etching and their hierarchical combinations ; and vacuum evaporated thin layer of ambipolar organic semiconductor, hydrogen-bonded pigment 6, 6′- dibromoindigo (tyrian purple). Our heterojunctions form rectifying junctions that are photo-sensitive in visible and NIR range, up to ~2500 nm. We show how micro- and nano- structuring of silicon substrates prior to organic thin-film evaporation increases the responsivity of our devices in the telecom C- band by up to 700 times in comparison to planar silicon substrates. We also show that this improvement cannot be due only to increased surface area and/or light trapping, and we present an alternative, electric-field dependant model of performance enhancement.

nanostructuring; silicon; organic semiconductor; devices

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