Solution-processed Metal Oxide Semiconductors Research Articles

(Invited) Low-Temperature Sol-Gel Derived Ultra-Flexible Metal-Oxide Thin-Film-Transistors and Their Applications

Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in amorphous state and excellent large-area uniformity have extended their applications to active-matrix electronics including displays, sensor arrays, and X-ray detectors. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics including wearable applications. However, metal oxide formation by sol-gel route requires a crucial annealing step at relatively-high temperature which impedes their incorporation onto the conventional polymeric substrates and thus high-performance flexible electronics. In this presentation, high performance solution-processed metal-oxide semiconductors as well as advancements in lowering processing temperature for thin-film-transistors (TFTs) and their applications for wearable electronics will be demonstrated. Additionally, the developments of advanced technologies for low-cost solution-processed metal-oxide TFT based sensor arrays and integrated circuits will be addressed.

Independent chemical/physical role of combustive exothermic heat in solution-processed metal oxide semiconductors for thin-film transistors

Based on newly-designed, solution-processable zinc tin oxide semiconductors, the independent contribution of combustive exothermic heat was investigated on chemical/physical structural evolution through spectroscopy analyses along with the interpretation on device performance.

Interrelation between Chemical, Electronic, and Charge Transport Properties of Solution-Processed Indium–Zinc Oxide Semiconductor Thin Films

Solution-processed metal oxide semiconductors are of high interest for the preparation of high-mobility transparent metal oxide (TMO) semiconductor thin films and thin film transistors (TFTs). It has been shown that the charge transport properties of indium–zinc oxide (IZO) thin films from molecular precursor solutions depend strongly on the preparation conditions, in particular on the precursor conversion temperature Tpc and, to some surprise, also on the concentration of the precursor solution. Therefore, the chemical and the electronic structure of solution-processed IZO thin films have been studied in detail with X-ray photoelectron spectroscopy (XPS) under systematic variation of Tpc and the concentration of the precursor solution. A distinct spectral feature is observed in the valence band spectra close to the Fermi level at EB = 0.45 eV binding energy which correlates with the trends in the sheet resistivity, the field effect mobility μFE, and the optical gap Egopt from four-point-probe (4PP), TFT, and UV–vis measurements, respectively. A comprehensive model of the interrelation between the conditions during solution-processing, the chemical and electronic structure, and the charge transport properties is developed.

Sub-second photo-annealing of solution-processed metal oxide thin-film transistors via irradiation of intensely pulsed white light

This study demonstrates the efficient photo-annealing of a solution-processed metal oxide active layer in thin film transistors by using intensely pulsed white light (IPWL) irradiation. The IPWL process offers the advantages of room-temperature processing and high processing speed of the order of milliseconds under ambient conditions. Analysis of the chemical composition of the IPWL-annealed thin films indicates that the IPWL irradiation provides sufficient heat energy to convert the molecular precursors to the respective metal oxides. A solution-processed amorphous In–Ga–Zn–O transistor annealed by IPWL irradiation exhibited improved electrical performance with a field-effect mobility of 2.67 cm2 V−1 s−1 and Ion/Ioff of 108. The suitability of IPWL for annealing other solution-processed metal oxide semiconductors was verified in IPWL-annealed Hf–In–Zn–O and In–Zn–O thin films.

ChemInform Abstract: Solution‐Processable Metal Oxide Semiconductors for Thin‐Film Transistor Applications

AbstractReview: 126 refs.

Solution-processable metal oxide semiconductors for thin-film transistor applications

In this review, we discuss the merits of solution-processed metal oxide semiconductors and consider their application in thin-film transistors for large-area electronics.

Transistors pick up steam

High annealing temperatures have limited the technological potential of solution-processed metal oxide semiconductors. It is now shown that high-quality films can be formed below 250 °C using precursors that are hydrolysed on-chip.