Boron-Doped Peroxo-Zirconium Oxide Dielectric for High-Performance, Low-Temperature, Solution-Processed Indium Oxide Thin-Film Transistor

Abstract

We developed a solution-processed indium oxide (In2O3) thin-film transistor (TFT) with a boron-doped peroxo-zirconium (ZrO2:B) dielectric on silicon as well as polyimide substrate at 200 °C, using water as the solvent for the In2O3 precursor. The formation of In2O3 and ZrO2:B films were intensively studied by thermogravimetric differential thermal analysis (TG-DTA), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT IR), high-resolution X-ray diffraction (HR-XRD), and X-ray photoelectron spectroscopy (XPS). Boron was selected as a dopant to make a denser ZrO2 film. The ZrO2:B film effectively blocked the leakage current at 200 °C with high breakdown strength. To evaluate the ZrO2:B film as a gate dielectric, we fabricated In2O3 TFTs on the ZrO2:B dielectrics with silicon substrates and annealed the resulting samples at 200 and 250 °C. The resulting mobilities were 1.25 and 39.3 cm(2)/(V s), respectively. Finally, we realized a flexible In2O3 TFT with the ZrO2:B dielectric on a polyimide substrate at 200 °C, and it successfully operated a switching device with a mobility of 4.01 cm(2)/(V s). Our results suggest that aqueous solution-processed In2O3 TFTs on ZrO2:B dielectrics could potentially be used for low-cost, low-temperature, and high-performance flexible devices.

Metal oxide semiconductor thin-film transistors for flexible electronics

“…Due to their high T G % 360 C, PI substrates with thickness ranging from %3 to 50lm are widely used. 83,145,191,193,[197][198][199][220][221][222][223] Polyarylate (PAR) foils have also been employed, 192,200,224,225 given their good temperature stability (T G % 330 C), combined with a colorless transparency in the visible range. If the semiconductor deposition is performed at lower temperatures ( 150 C), also PES foils (T G around 200 C) can be utilized.…”

“…The use of barrier layers for flexible ntype solution-processed metal oxide semiconductor devices is not very common. A few examples include c-PVP layers applied to planarize and smoothen the surface of PES or PI, 191,226 as well as PVP films utilized to reduce the surface roughness of PI foils from 3.6 nm down to 0.3 nm (root mean square). 232 145,197 Nevertheless, for solution-deposited metal oxide semiconductors, it is preferable to solution process also the gate dielectric, in order to further benefit from the lowcost large-area approach offered by solution-deposition processes.…”

“…29,115 Alternatives to Ga doping in IZO have also been developed, using tin (Sn), hafnium (Hf), and zirconium (Zr 76 including neat layers, nanoparticle (NP), or nanowire (NW) films, as well as blends of In 2 O 3 and polyvinylpyrrolidon (PVP). 76,145,[190][191][192] 83 either in the form of neat IGZO or in blends of IGZO and graphene nanosheets. 83,200,201 B.…”

Low-temperature spray-deposited indium oxide for flexible thin-film transistors and integrated circuits

“…A significant advantage associated with the application of In 2 O 3 in thin-film devices is that it can be grown at relatively low temperatures employing a diverse range of vapor-phase techniques, [10][11][12] as well as solutionbased methods. [13][14][15][16] 24 Furthermore, addition of suitable dopants in the precursor solution has also allowed the demonstration of Be-doped ZnO transistors and integrated circuits with optimized operating characteristics. 25 Despite the tremendous potential, however, deposition of semiconducting metal oxides by spray pyrolysis has so far been limited to high processing temperatures typically in excess of >350 C, hence rendering the technology incompatible with inexpensive, temperature-sensitive substrate materials such as plastic.…”

“…In order to investigate the charge transport properties of as-deposited In 2 O 3 films, we fabricated coplanar BG-BC transistors [ Figure 1 15,16 This is primarily attributed to the unfavourable coplanar BG-BC transistor architecture and the high work function gold S/D electrodes (À5 eV) used. 28 .…”