Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: Photovoltaics (joint session HL/CPP/O)

CPP 46.8: Talk

Friday, March 15, 2013, 11:00–11:15, H2

Solar diode sensor — •Hao Shen¹, Martin Hoffmann¹, Juan Daniel Prades², Francisco Hernandez-Ramirez³, and Andreas Waag¹ — ¹Institute of Semiconductor Technology, TU Braunschweig, D-38105 Braunschweig, Germany — ²Department of Electronics, Uni. Barcelona, E-08028 Barcelona, Spain — ³Catalonia Institute for Energy Research (IREC), E-08930 Barcelona, Spain

The nanodevice architecture presented here has been designed to overcome the current issues in gas sensor technologies: reducing power consumption and lowering operating temperature. Conductometric sensors based on semiconductor metal oxides need the continuous supply of the energy in the form of heat or UV light, to activate the chemical interaction between gases and the sensing surface. New concepts for energy harvesting units as an in-built module are demanded to make self-powered gas sensors. Herein we report a solar diode sensor (SDS) based on new designed CdS@n-ZnO/p-Si nanoelements which unifies gas sensing (CdS@n-ZnO) and solar energy harvesting (n-ZnO/p-Si diode) functionalities in a singular material unit and device. The SDS sensing mechanism (change of open circuit voltage), in comparison to the well-known conductometric sensors (change of resistance), is systematically studied and explained in terms of gas-material surface interactions and the subsequent changes in the doping level (ND), which is manifested in the variation of Voc in CdS@n-ZnO/p-Si. The fabricated SDS was capable of quantitatively detecting oxidising and reducing gases with reproducible response at room temperature and without the need of any other energy sources except solar illumination.