Feri Adriyanto

High-Mobility Pentacene-Based Thin-Film Transistors With a Solution-Processed Barium Titanate Insulator

Pentacene-based organic thin-film transistors (OTFTs) with solution-processed barium titanate (Ba_1.2Ti_0.8O₃) as a gate insulator are demonstrated. The electrical properties of pentacene-based TFTs show a high field-effect mobility of 8.85 cm² · V^-1 · s^-1, a low threshold voltage of -1.89 V, and a low subthreshold slope swing of 310 mV/decade. The chemical composition and binding energy of solution-processed barium titanate thin films are analyzed through X-ray photoelectron spectroscopy. The matching surface energy on the surface of the barium titanate thin film is 43.12 mJ · m^-2, which leads to Stranski-Krastanov mode growth, and thus, high mobility is exhibited in pentacene-based TFTs.

Pentacene-Based Thin-Film Transistors With a Solution-Process Hafnium Oxide Insulator

Pentacene-based organic thin-film transistors with solution-process hafnium oxide (HfOx) as gate insulating layer have been demonstrated. The solution-process HfOx could not only exhibit a high-permittivity (kappa = 11) dielectric constant but also has good dielectric strength. Moreover, the root-mean-square surface roughness and surface energy (gammas) on the surface of the HfOx layer were 1.304 nm and 34.24 mJ/cm2, respectively. The smooth, as well as hydrophobic, surface of HfOx could facilitate the direct deposition of the pentacene film without an additional polymer treatment layer, leading to a high field-effect mobility of 3.8 cm2/(V middots) .

AlGaN/GaN Metal–Oxide–Semiconductor High-Electron Mobility Transistor With Liquid-Phase-Deposited Barium-Doped

Barium-doped TiO2 films deposited on GaN layers at low temperature through a simple liquid phase deposition method is investigated. The use as a gate dielectric in AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) is also demonstrated. The electrical characteristics of the MOS structure on n-doped GaN show that the leakage current density is about 5.09 × 10-9 A/cm2 at 1 MV/cm, and the breakdown field is more than 13 MV/cm. The maximum drain current density of the AlGaN/GaN MOSHEMTs is higher than that of HEMTs, in which a wider gate voltage swing and a lower subthreshold swing (110 mV/decade) are obtained. The gate leakage current density is significantly improved, and the gate pulse measurement shows that the current collapse is more suppressed for MOSHEMTs.

\hbox{TiO}_{2}

High-performance pentacene-based thin-film transistors and inverters with solution-processed barium titanate (BTO) insulators are demonstrated. The current-voltage characteristics of the transistors show high mobility of 9.53 cm2 V-1 s-1 at smaller VG = -3.5 V and VD = -5 V, a low threshold voltage of -1.5 V, and a subthreshold slope of 599 mV/dec. Large grain and small crystalline sizes are observed from atomic force microscopy images and X-ray diffraction analysis of pentacene films. The results are verified through Raman spectroscopy and a theoretical Marcus-Hush equation to understand the higher intermolecular coupling, resulting in easier carrier transports in pentacene molecules. In order to investigate the behavior of high-permittivity materials of BTO insulators in a logic circuit, simple and low-operating-voltage inverters are fabricated, and the gain is approximately 8.76 under a small operating voltage range from 0 to -5 V.

as a Gate Dielectric

Solution processible poly(4-vinylphenol) is employed as a transistor dielectric material for low cost processing on flexible substrates at low temperatures. A 6,13-bis (triisopropylsilylethynyl) (TIPS) pentacene-graphene hybrid semiconductor is drop cast to fabricate bottom-gate and bottom-contact field-effect transistor devices on flexible and glass substrates under an ambient air environment. A few layers of graphene flakes increase the area in the conduction channel, and form bridge connections between the crystalline regions of the semiconductor layer which can change the surface morphology of TIPS pentacene films. The TIPS pentacene-graphene hybrid semiconductor-based organic thin film transistors (OTFTs) cross-linked with a poly(4-vinylphenol) gate dielectric exhibit an effective field-effect mobility of 0.076 cm(2) V(-1) s(-1) and a threshold voltage of -0.7 V at V(gs) = -40 V. By contrast, typical TIPS pentacene shows four times lower mobility of 0.019 cm(2) V(-1) s(-1) and a threshold voltage of 5 V. The graphene/TIPS pentacene hybrids presented in this paper can enhance the electrical characteristics of OTFTs due to their high crystallinity, uniform large-grain distribution, and effective reduction of crystal misorientation of the organic semiconductor layer, as confirmed by x-ray diffraction spectroscopy, atomic force microscopy, and optical microscopy studies.

High-Performance Pentacene-Based Thin-Film Transistors and Inverters With Solution-Processed Barium Titanate Insulators

The control dimension and morphology in zinc oxide (ZnO) nanorods are critical issues in the fabrication of electronic and optical nanodevices. This study discusses ZnO nanorods on an ITO-laminated plastic substrate of polyethylene terephthalate. The substrate was immersed in a zinc nitrate hexahydrate Zn(NO3)2.6H2O and hexamethylenetetramine C12H6N4. solution under various deposition conditions. The X-ray diffraction pattern showed that the films were composed of ZnO and Zn(OH)2, and that the ZnO crystal had strong x-ray reflection peaks (100 and 101), in which the c-axis was parallel to the substrate. To measure the elemental composition, the empirical formula, and the chemical state, X-ray photoelectron spectroscopy were used to examine the ZnO surface; peaks belonging to Zn and O were clearly detected. A larger surface roughness was achieved after adding a 0.20 M concentration of hexamethylenetetramine. The ZnO nanorods¿ microphotograph was found at a deposition temperature of 95° C and a 2 ml volume of 0.1 M NaOH. It was also found that the crystal shows a tip-nanorod morphology with a typical diameter of 0.3 ¿m and a 3.0 ¿m rod length.