1St International Conference on Organic Electronic Material Technologies (OEMT2015) March

1st International Conference on Organic Electronic Material Technologies (OEMT2015) March 25-28, 2015 Elazığ, TURKEY

High mobility Copper (II) Phthalocyanine Based Field Effect Transistors with organic /inorganic bilayer gate dielectric

Serif Ruzgar*1, Mujdat Caglar1

1Department of Physics, Anadolu University, Eskisehir, Turkey

*E-mail:

1st International Conference on Organic Electronic Material Technologies (OEMT2015) March 25-28, 2015 Elazığ, TURKEY

Organic materials suggest numerous advantages for easy processing (e.g., evaporation, spin coating, printing), good suitability with a variety of substrates including flexible plastics and great opportunities in structural modifications. Among the wide range of organic semiconductors considered, metal phthalocyanines are one of the most promising candidates to be used in the fabrication of such organic devices [1]. Phthalocyanines are small organic molecules characterized by high symmetry, planarity and electron delocalization. Otherwise, Phthalocyanines can be easily sublimed in high vacuum systems resulting in high-purity thin films with excellent growth properties and chemical stability, taking into account that the use the sublimation technique allows the deposition of thin films with controlled thickness and structural properties [2].

In this study, Copper(II) Phthalocyanine (CuPc) based organic field effect transistors (OFET) with top contacts bottom gate configurations were fabricated. Initially aluminum gate contact of thickness of 100 nm was deposited on pre cleaned glass surfaces. A part of Al film was then anodized to form Alumina (Al2O3) layer to be used a gate dielectric layer. In order to achieve a smooth interface between gate dielectric and organic channel, we spin-coated Polyvinyl alcohol (PVA) layer on Al2O3 surface. As an active layer CuPc thin-film with 50 nm thickness was evaporated on PVA dielectric layer by using thermal evaporation method (Vaksis PVD Handy-MT/101T, Turkey). The grained structure of CuPc film is shown in Fig. 1. After the deposition of the CuPc film, finally the source and drain electrodes were prepared by evaporating a 125 nm Au layer through a shadow mask. The channel width and length of the transistor are 1000 µm and 50 µm, respectively.

Figure 1. SEM micrograph of CuPc film.

Figure 2. Schematic structure of CuPc based-FET

Fig. 2 shows the schematic structure of CuPc based-FET. The electrical measurements of CuPc based-FET were performed using a KEITHLEY 4200 SCS/CVU semiconductor characterization system with connected SIGNATONE Semi-Atomatic Probe Station at room temperature under dark condition. The CuPc based-FET exhibited a p-channel behavior (Fig. 3). The mobility, Ion/Ioff ratio and threshold voltage for this device were found to be 6×10−2 cm2 V−1 s−1, ~ 103 and -3 V, respectively.

Figure 3. Output characteristics of CuPc- based-FET

[1] T. Sekitani, U. Zschieschang, H. Klauk, and T. Someya, Nat. Mater. 9 (12), 1015–1022 (2010)

[2] W. Brütting, Physics of Organic Semiconductors, Wiley–VCH, Weinheim, 2005