• Hambsch, Mike
• Wrzesińska, Angelika
• Dornack, Christina
• Haase, Katherina
• Tahn, Alexander
• Pohl, Darius
• Rellinghaus, Bernd
• Dacha, Preetam
• Maletz, Roman
• Mannsfeld, Stefan C. B.
• Millek, Vojtech
• Vaynzof, Yana

Abstract

Sol–gel-based solution-processed metal oxides have emerged as a key<br/>fabrication method for applications in thin film transistors both as a<br/>semiconducting and a dielectric layer. Here, a low-temperature, green<br/>solvent-based, non-toxic, and cost-effective solution shearing approach for the<br/>fabrication of thin aluminum oxide (AlOx) dielectrics is reported. Optimization<br/>of sustainability aspects like energy demand, and selection of chemicals used<br/>allows to reduce the environmental impact of the life cycle of the resulting<br/>product already in the design phase. Using this approach, ultra-thin,<br/>device-grade AlOx films of 7 nm are coated—the thinnest films to be reported<br/>for any solution-fabrication method. The metal oxide formation is achieved by<br/>both thermal annealing and deep ultra-violet (UV) light exposure techniques,<br/>resulting in capacitances of 750 and 600 nF cm−2, respectively. The structural<br/>analysis using microscopy and x-ray spectroscopy techniques confirmed the<br/>formation of smooth, ultra-thin AlOx films. These thin films are employed in<br/>organic field-effect transistors (OFETs) resulting in stable, low hysteresis<br/>devices leading to high mobilities (6.1 ± 0.9 cm2 V−1 s−1), near zero threshold<br/>voltage (−0.14 ± 0.07 V) and a low subthreshold swing (96 ± 16 mV dec−1),<br/>enabling device operation at only ±0.5 V with a good Ion/Ioff ratio (3.7 × 105).

Topics

• impedance spectroscopy
• phase
• thin film
• aluminum oxide
• aluminium
• annealing
• X-ray spectroscopy
• microscopy