In this study, photonic curing is used to rapidly and effectively convert metal-oxide sol−gels to realize high-quality thin-film transistors (TFTs). Photonic curing offers advantages over conventional thermal processing methods such as ultrashort processing time and compatibility with low-temperature substrates. However, previous work on photonically cured TFTs often results in significant heating of the entire substrate rather than just the thin film at the surface. Here, sol−gel indium zinc oxide (IZO)-based TFTs are photonically cured with efficient gate absorbers requiring as few as five pulses using intense white light delivering radiant energy up to 6 J cm −2 . Simulations indicate that the IZO film reaches a peak temperature of ∼590 °C while the back of the substrate stays below 30 °C. The requirements and design guidelines for photonic curing metal-oxide semiconductors for high-performance TFT applications are discussed, focusing on the importance of effective gate absorbers and optimized pulse designs to efficiently and effectively cure sol−gel films. This process yields TFTs with a field-effect mobility of 21.8 cm 2 V −1 s −1 and an I on /I off ratio approaching 10 8 , which exceeds the performance of samples annealed at 500 °C for 1 h. This is the best performance and highest metal-oxide conversion for photonically cured oxide TFTs achieved to date that does not significantly heat the entire thickness of the substrate. Importantly, the conversion from sol−gel precursors to the semiconducting metal-oxide phase during photonic curing is on par with thermal annealing, which is a significant improvement over previous pulsed-light processing work. The use of efficient gate absorbers also allows for the reduction in the number of pulses and efficient sol−gel conversion.

Fabricating flexible electronics on plastic is often limited by the poor dimensional stability of polymer substrates. To mitigate, glass carriers are used during fabrication, but removing the plastic substrate from a carrier without damaging the electronics remains challenging. Here we utilize a large-area, high-throughput photonic lift-off (PLO) process to rapidly separate polymer films from rigid carriers. PLO uses a 150 µs pulse of broadband light from flashlamps to lift-off functional thin films from glass carrier substrates coated with a light absorber layer (LAL). Modeling indicates that the polymer/LAL interface reaches above 800 °C during PLO, but the top surface of the PI remains below 120 °C. An array of indium zinc oxide (IZO) thin-film transistors (TFTs) was fabricated on a polyimide substrate and photonically lifted off from the glass carrier. The TFT mobility was unchanged by PLO. The flexible TFTs were mechanically robust, with no reduction in mobility while flexed.

<div>Metal oxides have been investigated for use in displays and wearable electronics, owing to their high mobility in the amorphous state. In solution-processed oxide thin-film transistors, post-deposition thermal processing significantly change the film’s transport properties, and is essential for high-performance devices. The mobility, bias stability and trapping-detrapping related hysteresis are improved with higher processing temperatures, which is generally attributed to decreased localized states which act as electron traps. Here we develop a model to validate that post-deposition processing indeed changes the density and properties of the localized states. We obtain good agreement between this model and the experimental data measured from sol-gel indium zinc oxide TFTs. When the processing temperature increases from 300 to 500 ⁰C, the model indicates that the trap state density in the bulk semiconductor and at the interface decrease by a factor of 5 and a factor of 3, respectively. Furthermore, the localized states become shallower, and the band mobility increases at higher processing temperatures.</div>

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