In this study, we examine the electrical properties of diketopyrrolopyrrole (DPP) containing polymer semiconductors that have been reported to show high performance with ambipolar characteristics. We prepared three different DPP based polymer semiconductors (PDPPTPT, PDPP3T, and PDPP2T-TT) and fabricated organic thin film transistors (OTFTs) with ambipolar polymer semiconductors as an active layer. All three DPP polymers showed only p-type properties at initial measurements. However, after annealing in vacuum oven for 24 hours, it was found that the DPP based polymers have both p-type and n-type properties. It is speculated that the residual impurities supposedly regarded as a strong electron trap source were eliminated during the vacuum process.

Al2O3 films on silicon carbide were fabricated by Aerosol deposition with annealing temperatureat 800℃ and 1,000℃. The effect of thermal treatment on physical properties of Al2O3 thin films has beeninvestigated by XRD (X-ray diffraction), AFM (atomic force microscope), SEM (scanning electronmicroscope), and AES (auger electron spectroscopy). Also electrical properties have been investigated byKeithley 4,200 semiconductor parameter analyzer to explain the interface trapped charge density (Dit),flatband voltage (VFB) and leakage current (Io). Al2O3 films become crystallized with increasingtemperature by calculating full width at half maximum (FWHM) of diffraction peaks, also surfacemorphology is observed by topography measurement in non-contact mode AFM. Dit was 2.26×10-12eV-1.cm-2 at 800℃ annealed sample, which is the lowest value in all samples. Also the sample annealedat 800℃ has the lowest leakage current of 4.89×10-13 A.