IJRRAS 12 (2) ● August 2012 www.arpapress.com/Volumes/Vol12Issue2/IJRRAS_12_2_11.pdf 244 ORGANIC TRANSISTORS FIELD EFFECT PERFORMANCES Ouiza Boughias 1,* , Mohamed-Said Belkaid 1 , Farida Nemmar 1 & Djedjiga Hatem 1 1 Laboratory of Advanced Technologies of Genie Electrics. Electronics Department. 1 The University of Mouloud Mammeri B.P.N°17 R.P 15000, Tizi-Ouzou, Algeria ABSTRACT In the late 70 the researchers have shown the existence of electrically conductive polymers. For this the polymer must be conjugate which have give birth to organic electronics. This field of research motivates seriously some industrial. The conductor polymers are used like active layer in the devices like as organics transistors, solar cells and electroluminescent leds. Organic transistors field effects are particulary interesting because their manufacturing processes are much low complex and low cost than their equivalents made from inorganic materials. Among the parameters characterizing the organic transistors we find the switching speed which is the fraction of the mobility of charge carriers through the conduction channel length. The organic transistors must submit an acceptable life during because the organic semiconductor materials are sensitive to oxygen and humidity. The advantages of organic transistors to classical transistors are light weight, flexibility and low cost of manufacturing process at large surface. In this paper, we study the electrical proprieties of organic transistor and compare it to classical transistors. Keywords: Organic field effect transistor, Organic MOSFET transistor,Pentacene, High-k. 1. INTRODUCTION Integrate circuits are constituted of many transistors, thus, the improvement of individual transistor performances involves the development of integrated circuits. Among the different ways of this improvement, we find the use of organic materials as an active layer. It consists on the replacement of silicon by conjugated polymers or small molecules. These organic materials are called polymers. They are insulating because they do not lead an electrical current, but after modification they become conducting of electricity if they are conjugated. Conjugated polymers in their undoped state are used like active layer in organic electronic devices. To satisfy the specification sheets, we should have a compromise between the material mobility and the transistor geometry. So, we should choose high mobility materials for the active layer transistor or reduce transistor geometry. 2. STRUCTURE OF CLASSICAL FIELD EFFECT TRANSISTORS The MOSFET transistor consist of four electrodes source (S), drain (D), gate (G) and bulk (B). The source and the drain are separated by the semiconductor which is mono-silicon The gate, which is poly-silicon with high doped, is separated from the semiconductor with an insulator, which is silicon oxide (SiO 2 ) as shown in “Fig.1”. Figure 1.Classical field effect transistor. The voltage applied to the gate determines the current which flows between source and drain, this voltage may be superior to same value called threshold voltage (V th ). For negative gate voltage, the holes are attired at the interface of silicon / silicon oxide. If we increase the gate voltage under the electrical field effect, the holes are pushed to the surface until these latter comport only negative fixes charge. If the gate voltage is greater than threshold voltage (V G > V th ), the electrons will be attracted to the drain under the longitudinal electrical field effect created by V DS positive voltage. 3. STRUCTURES OF ORGANIC FIELD EFFECT TRANSISTORS Organic field effect transistors are based on MIS (Metal-Insulator-Semiconductor) type structure in its fabrication. This structure in organics field effect transistors is used to get two kinds of transistors: top contact transistor (“Fig. 2.a”) and bottom contact transistor (“Fig. 2. b”). Source Semiconductor Drain Insulator Bulk Gate