Low power organic field effect transistors with copper phthalocyanine as active layer

Bottom gate, top contact Organic Field Effect Transistors (OFETs) were fabricated using copper phthalocyanine (CuPc) as an active layer. The electrical properties of OFETs fabricated with CuPc annealed at different annealing temperatures and different channel length to width (L/W) ratios were studied. The transfer characteristics of the devices appear to improve with annealing temperature of CuPc and increasing L/W ratios of the devices. Upon annealing, the field effect mobility increased from 0.03 ± 0.004 cm2/V to 1.3 ± 0.02 cm2/V. Similarly, the interface state density reduced from 5.14 ± 0.39 × 1011 cm−2eV−1 for the device fabricated using as deposited CuPc, to 2.41 ± 0.05 × 1011 cm−2eV−1 for the device with CuPc annealed at 80 °C. The on/off current ratio increased from 102 for the as-deposited device, to 105 for the device with CuPc annealed at 80 °C. The dependence of the subthreshold swing on the L/W ratio was also investigated. Keywords: Organic field effect transistors, CuPc, Scanning tunneling microscope, Interface trap density, Carrier mobilit