Sublimation-doping with super bases for high-performance solution-processed heterojunction oxide thin film...

Area of Science:

• Materials Science
• Electronics
• Semiconductor Physics

Background:

• Solution-processed heterojunction oxide thin-film transistors (TFTs) are crucial for electronic applications.
• Controlling band bending in Indium Oxide/Zinc Oxide (In2O3/ZnO) heterojunctions is key to enhancing TFT performance.
• Non-destructive doping methods are sought to improve device characteristics.

Purpose of the Study:

• To investigate the effect of non-destructive sublimation-doping using amidine-based organic dopants on In2O3/ZnO heterojunctions.
• To correlate dopant basicity with band bending and electron mobility in TFTs.
• To optimize sublimation-doping for high-performance and stable oxide TFTs.

Main Methods:

• Sublimation-doping of In2O3/ZnO heterojunctions with various organic dopants.
• Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) for electronic structure analysis.
• Mott-Schottky analysis and secondary ion mass spectroscopy (SIMS) for band bending and doping profiles.
• Fabrication and characterization of solution-processed TFTs.

Main Results:

• Stronger dopant basicity led to reduced E_C - E_F in ZnO, increasing electron density in the In2O3 layer near the interface.
• Mott-Schottky and SIMS analyses confirmed preferential modification of E_C - E_F in the ZnO layer.
• Using a super base dopant resulted in high electron mobility (17.8 cm^2 V^-1 s^-1 on SiO2, 37.8 cm^2 V^-1 s^-1 on ZrO2).
• Enhanced operational bias-stress stability was achieved with optimized sublimation-doping.
• Reproducibility demonstrated with <±10% deviation in electron mobility across over 50 fabricated TFTs.

Conclusions:

• Non-destructive sublimation-doping with organic super bases is an effective method to enhance electron mobility and stability in In2O3/ZnO TFTs.
• The degree of dopant basicity critically influences band bending and charge transport characteristics.
• This doping strategy offers a promising route for fabricating reliable, high-performance oxide TFTs.