Mazran Bin Esro

Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (LaxAl1−xOy) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the LaxAl1−xOy films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlOy dielectrics exhibit a wide band gap (∼6.18 eV), high dielectric constant (k ∼ 16), low roughness (∼1.9 nm), and very low leakage currents ( 106, subthreshold swing of ∼650 mV dec−1, and electron mobility of ∼12 cm2 V−1 s−1.We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (LaxAl1−xOy) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the LaxAl1−xOy films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlOy dielectrics exhibit a wide band gap (∼6.18 eV), high dielectric constant (k ∼ 16), low roughness (∼1.9 nm), and very low leakage currents ( 106, subthreshold swi...

Solution processed SnO2:Sb transparent conductive oxide as an alternative to indium tin oxide for applications in organic light emitting diodes

Here, we present the deposition of antimony-doped tin oxide thin films using the ambient spray pyrolysis technique and demonstrate their implementation as transparent electrodes (anodes) in red, green and blue organic light emitting diodes. The films were spray coated at 380 °C from SnCl4 and SbCl3 solution blends in methanol and ∼230 nm thick films were investigated by means of X-ray diffraction, AFM, UV-Vis absorption spectroscopy, 4-point probe, Hall effect measurements and Kelvin probe. It was found that for optimum antimony doping in the precursor solution of ∼2 wt%, the as-deposited ATO films exhibit excellent characteristics such as a low surface roughness (RRMS) of ∼ 6.3 nm, a high work function (∼−5.03 eV), a wide direct band gap (∼4.2 eV), high transparency in the visible spectrum in excess of 85% on glass, a low sheet resistivity (∼32 Ohms sq−1), a high charge carrier concentration (∼6.35 × 1020 cm−3) and a carrier mobility of ∼32 cm2 V−1 s−1. Furthermore, the electrical and optical performance i.e. the turn on voltage and external quantum efficiency of red, green and blue OLEDs fabricated on optimized SnO2:Sb films were identical to those of OLEDs fabricated on commercially available ITO (Rs ∼ 15 Ohms sq−1) and were found to be in excess of 11%, 0.3% and 13% for red, green and blue OLEDs, respectively.

Structural and Electrical Characterization of SiO2 Gate Dielectrics Deposited from Solutions at Moderate Temperatures in Air

Silicon dioxide (SiO2) is the most widely used dielectric for electronic applications. It is usually produced by thermal oxidation of silicon or by using a wide range of vacuum-based techniques. By default, the growth of SiO2 by thermal oxidation of silicon requires the use of Si substrates whereas the other deposition techniques either produce low quality or poor interface material and mostly require high deposition or annealing temperatures. Recent investigations therefore have focused on the development of alternative deposition paradigms based on solutions. Here, we report the deposition of SiO2 thin film dielectrics deposited by spray pyrolysis in air at moderate temperatures of ≈350 °C from pentane-2,4-dione solutions of SiCl4. SiO2 dielectrics were investigated by means of UV-vis absorption spectroscopy, spectroscopic ellipsometry, XPS, XRD, UFM/AFM, admittance spectroscopy, and field-effect measurements. Data analysis reveals smooth (RRMS < 1 nm) amorphous films with a dielectric constant of about 3.8, an optical band gap of ≈8.1 eV, leakage current densities in the order of ≈10-7 A/cm2 at 1 MV/cm, and high dielectric strength in excess of 5 MV/cm. XPS measurements confirm the SiO2 stoichiometry and FTIR spectra reveal features related to SiO2 only. Thin film transistors implementing spray-coated SiO2 gate dielectrics and C60 and pentacene semiconducting channels exhibit excellent transport characteristics, i.e., negligible hysteresis, low leakage currents, high on/off current modulation ratio on the order of 106, and high carrier mobility.