Schottky barrier height tuning by Hybrid organic-inorganic multilayers
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Schottky barrier height tuning by Hybrid organic-inorganic multilayers V. Torrisi1, M. A. Squillaci1, F. Ruffino2, I. Crupi2, M.G. Grimaldi2, G. Marletta1 1
Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale A. Doria 6, 95125, Catania, Italy. 2
Dipartimento di Fisica ed Astronomia-Università di Catania, and MATIS IMM-CNR, via S. Sofia 64 95128 Catania, Italy. ABSTRACT Semiconducting and insulating polymers and copolymers/Au nanograins based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate by an iterative method that involves, respectively, Langmuir-Blodgett and spin-coating techniques (for the deposition of organic film) and sputtering technique (for the deposition of metal nanograins) to prepare Au/HyMLs/p-Si Schottky device. The electrical properties of the Au/HyMLs/p-Si Schottky device were investigated by current-voltage (I–V) measurements in the thickness range of 1-5 bilayers (BL). At different number of layers, current-voltage (I–V) measurements were performed. Results showed a rectifying behavior. Junction parameters, such as barrier height (BH), from the I–V measurements for example for the PMMA-b-PS based Au/HyMLs/p-Si structure were obtained as 0.72±0.02 eV at 1BL and 0.64±0.02eV at 5BL. It was observed that the BH value of 0.61 eV obtained for the 5 BL PS based Au/HyMLs/p-Si structure was lower than the value of 0.68 eV of conventional Au/p-Si Schottky diodes. Thus, modification of the interfacial potential barrier for Au/p-Si diodes has been achieved using a thin MLs of different polymers based HyMls semiconductor. INTRODUCTION The Barrier Height (BH) is the fundamental parameter for the rectifying contacts, and, recently, many attempts have been made to realize the modification and the continuous control of the BH using an organic semiconducting layer1-12. The organic–inorganic hybrid device is expected not only to permit a wide ranging selection of emitter and carrier transport materials but also to provide an alternative approach to construct high-performance electronic devices taking advantages of both the organic and inorganic semiconductors. In this work, we show the electrical effects on a Schottky device produced by the insertion at Metal-Semiconductor (MS) interface of nanometer hybrid polymer/metal multilayers based on insulating and semiconducting polymers. Hybrid multilayers (HyMLs) are tunable systems; in fact they offer the possibility to tune the thickness of inserted components at the MS interface. Because of this peculiarity, HyMLs are the suitable systems for the continuous control and modification of the BH of a Schottky device. The metal/hybrid/semiconductor Schottky diode not only shows the potential to improve the BH but also attracts us to investigate the information about organic/inorganic interface. Furthermore polymer/metal HyMLs combine structural flexibility, convenient
processing, tunable electronic properties of polymeric layers and high carrier mobilities, therm
