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The influence of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) agglomerated nanostructure on device performance of pentacene-based organic thin-film transistors (OTFTs) were reported. The presence of PCBM layers on a SiO2 gate dielectric resulted in a good electrical characteristics of pentacene-based OTFTs, including a relatively high mobility (μ = 0.95-2.2 cm2 V-1 s-1), low threshold voltages (Vth = -1.1 - -5.4 V), a high on/off current ratio (Ion/Ioff = 104), and a high value of subthreshold slope (SS = 6.5 V/decade). The surface topography studies reveal that the PCBM nanostructure could favor the reduction of grain boundaries, which resulted in a better transistor performance of pentacene-based OTFTs. The influence of PCBM on the molecular microstructure of pentacene thin films elucidates a reasonable explanation for higher performance on OTFTs.

Oxide materials have been widely used in opto-electro devices due to their wide bandgap energy, high optical transparency in the visible light region, and wide range resistance. Recently, delafossite CuMO2 (M=Al, Ga, In) have been widely studied for p-type oxide semiconductors. In this study, CuGaO2 was chosen due to its smaller lattice mismatch with ZnO compared with CuAlO2 for the possibility of p-n junction device in the future work. Zn as impurity atoms was introduced to fabricate quaternary CuZnGaO2 films to reduce lattice mismatch with ZnO. In order to study the effect of the substitute site of the Zn ion for generating donor or acceptor, 3 methods of preparation of the Cu-Zn-Ga-O sol solution were also demonstrated. In this paper, the electrical and structural properties of Zn doped on the sol-gel derived CuGaO2 films have been investigated. The diffraction angle of the CuGaO2 films are shifted to lower angle with increasing Zn%, indicating the lattice expansion which proved that the introducing Zn as impurity atoms was able to reduce lattice mismatch between CuGaO2 and ZnO. While the curve in the negative gate bias Vg proved the hole dominated transport properties. The curve in the positive gate bias can be suppressed by introducing Zn.

We introduce a charge-accepting layer on a gate dielectric to investigate the reversible threshold voltage (V th ) shifts in both p-channel and n-channel organic field-effect transistors (OFETs) using organic semiconductors of pentacene and poly-naphthalene dicarboximide [P(NDI2OD-T2)], respectively. Bottom gate with top drain-source contact structure of both devices exhibited a unipolar property of field-effect transistor behavior. Furthermore, the existence of fullerene (PCBM) and poly(3-hexylthiophene) (P3HT) films as a charge-accepting-like storage layers in p-channel and n-channel devices, respectively, resulted in a reversible V th shifts upon the application of external gate bias (V bias ). Hence, p-channel OFETs exhibited a memory window of 2.4 V and n-channel OFETs exhibited a memory window of 10.7 V for program and erase electrically upon application of gate bias.

We introduce an hole-accepting layer on a poly(methyl methacrylate) (PMMA) dielectric to investigate the reversible threshold voltage (Vth) shifts in all-polymer nchannel organic field-effect transistor (OFET) using an organic semiconductor of an poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)). Top drain-source with a bottom-gate contact structure device exhibited a unipolar property with n-channel behavior. Furthermore, the existence of poly(3-hexylthiophene) (P3HT) films as a hole-accepting-like storage layers resulted in a reversible Vth shifts upon the application of external gate bias (Vbias). Hence, all-polymer organic transistor with the hole-accepting layer exhibited a large memory window (?Vth = 10.7 V) for write and erase electrically without major degradation in saturation mobility (μsat = 1.8~2.8×10-4 cm2 V-1 s-1).

Organic semiconductors have been the subject of interest for the past decade. Despite significant progress in the p-channel organic thin-film transistors (OTFTs), there are still problems concerning the development of n-channel OTFTs owing to the selection of n-channel organic materials, which are limited to a very small number of molecules and polymers [1], and also serious drawbacks, including poor solubility, difficulty of synthesis and unstable transistor operation under ambient atmosphere [2]. Since the first air-stable n-channel OTFTs based on naphthalenetetracarboxylic diimides was reported [3], a large number of n-channel organic materials have been based on either naphthalene diimide (NDI) — or perylene diimide (PDI)-based polymers. It is therefore clear that n-channel organic materials have an important role in the continuing development of organic-based circuits and products. In this study, we focused to elucidate the fabrication and characterization of n-channel OTFTs based on poly{[N, N'bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} [P(NDI2D-T2)]. Moreover, we also demonstrate organic transistor memory with an n-channel P(NDI2OD-T2) OTFTs using poly(3-hexylthiophene) (P3HT) as the charge trapping layer.

The energy levels of organic semiconductor materials; poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61 -butyric acid methyl ester (PCBM), were investigated using photo-electron spectroscopy in air (PESA) and UV-Vis spectrophotometer. Solution-processed organic thin-film transistors (OTFTs) based on P3HT/PCBM blend thin film in a top source-drain contact structure was fabricated, and the optical response and memory effects of the devices were also investigated. A unipolar property with p-channel characteristics were obtained in dark condition, and upon an optical response, the drain current was increased. Moreover, the drain current was decreased gradually with delay time after turning off the light, while negative gate bias was required to revert back to initial dark condition. The memory effects of the P3HT/PCBM-OTFTs were attributed to the photocurrent induction and electron trapping-detrapping capability of PCBM nanoparticles. The optical-electro memory effect based on the OTFTs can be programmed optically and erased electrically.

Sub-half-micrometer dual-gate CMOSFETs have been successfully fabricated with 6-nm-thick nitrided SiO/sub 2/ gate films formed in an N/sub 2/O ambient. Excellent subthreshold characteristics and hot-carrier reliability were achieved because of the good abilities of N/sub 2/O-nitrided SiO/sub 2/ films in both blocking boron penetration and reducing electron traps. The major advantage of this nitridation is that the process is essentially hydrogen-free. This fabrication process is promising as a key technology toward 1/4- mu m-rule CMOS LSIs. >