Réalisation de dispositifs microélectroniques à base de films organiques

Abstract

This thesis focuses on the realization of microelectronic devices based on organic materials. In order to develop next generation devices those have applications in the topic of solarphotovoltaic energy. Organic semiconductors based MetalPhthalocyanine appear as an alternative to inorganic semiconductors and represent a promising technology for economic and environmental issues. Our research involves the fabrication and characterization of devices based MetalPhthalocyanine (MPc). We have set up an experimental protocol of microelectronic devices (Schottky diodes) based MPc achievement. In the first step, we make thin films based on MgPc, ZnPc, AlPc-Cl and AlPc-H on several substrates glass, n-GaAs, InP-p, n-Si and p-Si. The selected thin films deposited on glass substrate are then investigated by X-ray pattern, UV-VIS-IR, Raman diffusion, AFM-SEM observation means. In the second step, the selected layers deposited on n-GaAs, InP-p, n-Si and p-Si are the tools of the organic device fabrication. Our fabricated devices form the Schottky diodes and the microelectronic properties are then studied. The preparation of thin films and fabrication of Schottky diodes are achieved by the spin-coating and thermal evaporation under vacuum techniques. At room temperature, the achieved electrical measurements of MPC organic Schottky diodes are current-voltage in dark-light and capacitance-voltage under dark condition. Based on physical properties study of thin layers (MgPc, ZnPc and AlPc-Cl) deposited on glass, we confirm the formation of MPc phase and the nanogranular structure of such layers G~ 1 nm. Besides the films are transparent semiconductors owing an indirect wide band gap of 2.8 eV and present vibrational modes. MPc layers have a smooth (RMS ~1 0 nm) surface morphology and nanograins grow along z-axis. As mentioned earlier, we have made 12 kinds of organic devices. The measurement of the (I-V) characteristic under light and dark, and the (C-V) and (G / ω-V) measurements allow extracting many microelectronic and photovoltaic parameters such as ideality factor, series resistance, barrier height, rectifying parameter, interface density, open circuit voltage, short circuit current, photosensitivity, fill factor, efficiency, donor and acceptor carrier densities and potential in built. The well known approximation methods of parameters calculation Cheung-Cheung and Norde are used. Conduction mechanisms of such organic structures are widely investigated in one hand and effect of substrate and organic layer on electronic properties is also largely studied in other hand. The Schottky diodes based on MgPc have shown excellent performance for different structures (Ag/MgPc/n-Si/Au, Ag/MgPc/p-InP/Au-Zn and Ag/MgPc/n-GaAs/Au-Ge). Consequently, the organic MgPc device is the best candidate for applications in microelectronics and the solar photovoltaic compared to ZnPc, AlPc-Cl and AlPc-H.