Electronic properties of ZnO field-effect transistors fabricated by spray pyrolysis in ambient air

Abstract

We report the application of spray pyrolysis (SP) for the deposition of high quality zinc oxide (ZnO) films and the fabrication of thin-film transistors. The chemical, structural, optical, and electronic properties of as-deposited ZnO films are studied using infrared spectroscopy, atomic force microscopy, UV-visible spectroscopic ellipsometry, and field-effect measurements. SP ZnO films are found to be uniform and polycrystalline with a band gap of 3.32 eV. ZnO transistors exhibit n-channel characteristics with electron mobility in the range 10–22 cm2/Vs. Device performance is found to depend on the work function of source/drain metal electrodes and on the device architecture employed.

Influence of anneal atmosphere on ZnO-nanorod photoluminescent and morphological properties with self-powered photodetector performance

“…These properties, as well as the relative ease with which ZnO nanostructures can be grown, lend themselves to use in nanoscale field effect transistors, 1 antireflection coatings, 2 energy-harvesting, [3][4][5] and optoelectronic 6,7 devices. ZnO nanorods can be synthesised at low-temperatures (<100 C) using aqueous chemical growth from a variety of chemical precursor mixtures such as zinc nitrate hexahydrate (Zn(NO) 3 Á6H 2 O) and hexamethylenetetramine (HMT).…”

High‐Mobility Low‐Voltage ZnO and Li‐Doped ZnO Transistors Based on ZrO2 High‐k Dielectric Grown by Spray Pyrolysis in Ambient Air

“…[35][36][37][38][39] Here we demonstrate how spray pyrolysis (SP), a simple and large-area-compatible deposition technique, can be used for the processing of high-quality ZrO 2 layers onto glass substrates containing prepatterned indium tin oxide (ITO) electrodes. We demonstrate their use in high-mobility, low-voltage TFTs based on either ZnO or Li-doped ZnO fi lms deposited by SP [10][11][12][13][14] directly onto ITO/ZrO 2 . Optimised TFTs based on ITO/ZrO 2 / Li-ZnO multilayer structures deposited sequentially at substrate temperatures of 400-450 ° C exhibit excellent electrontransport characteristics with operating voltages below 6 V and a maximum electron mobility on the order of 85 cm 2 V − 1 s − 1 .…”

Spray‐Deposited Li‐Doped ZnO Transistors with Electron Mobility Exceeding 50 cm2/Vs

“…For example, metal oxides such as zinc oxide (ZnO) [17][18][19][20][21][22] , indium oxide (In 2 O 3 ) [23][24] , indium gallium oxide (InGaO) [25] , indium zinc oxide (InZnO) [18][19][20][21][22][23][24][25][26] and zinc tin oxide (ZnSnO) [27] have been synthesised using soluble precursors and implemented into TFT structures. Despite the process simplicity, excellent charge carrier mobilities have been achieved, clearly demonstrating the significant potential of this alternative processing methodology.…”

“…[28] One interesting observation is that short channel (<30 µm) Li-ZnO TFTs show higher electron mobilities as compared to long channel devices (>20 µm). The effect is attributed to grain boundary limited electron transport [21,29] . This effect is better illustrated in Figure 2c where the saturated electron mobility, obtained from a number (e.g.…”

“…The optical band gap has also been calculated using spectroscopic ellipsometry (SE) measurements at the spectral region from 1.5 to 4.5 eV. [21] Figures S5 and S6 provide further details on the evolution of the infinite refractive index and voids used in the modelling as well as the real, imaginary dielectric function parts and reflection dispersions for the film that shows the highest field effect mobility. They are all consistent with the trends reported above.…”