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Giant persistent photoconductivity in rough silicon nanomembranes
Ping Feng1, Ingolf Mönch, Stefan Harazim
1Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany. y.mei@ifw-dresden.de
Nano Letters
|July 30, 2009
Summary
Giant persistent photoconductivity was observed in rough silicon nanomembranes. Light exposure dramatically increased conductivity for days, tunable with gate voltage, due to localized holes activated by light.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Silicon nanomembranes (Si NMs) are promising materials for electronic devices.
- Persistent photoconductivity (PPC) is a phenomenon where conductivity remains elevated after light removal.
- Understanding PPC in Si NMs is crucial for advanced optoelectronic applications.
Purpose of the Study:
- To investigate the origin of giant persistent photoconductivity in rough Si nanomembranes.
- To explore the influence of surface morphology and gate voltage on PPC.
- To elucidate the mechanism behind light-induced conductivity enhancement and persistence.
Main Methods:
- Fabrication of p-type Si nanomembranes with controlled surface roughness.
- Measurement of photocurrent under varying light conditions and applied gate voltages.
- Surface analysis and band structure characterization using coatings.
Main Results:
- Observed a giant PPC effect, enhancing current by ~3 orders of magnitude.
- Photoconductivity persisted for days after light removal.
- Gate voltage demonstrated control over photocurrent magnitude and response time.
- Attributed the effect to hole localization in Si NMs caused by surface roughness.
Conclusions:
- Roughness-induced hole localization in Si NMs is the key mechanism for giant PPC.
- Si nanomembranes exhibit potential for long-lasting photoresponsive devices.
- Gate-tunable persistent photocurrent opens avenues for novel electronic applications.
