Reversible Charge Transfer Doping in Atomically Thin In₂O₃ by Viologens

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Atomically thin oxide semiconductors are crucial for 3D integration and sensors.
• Controlling carrier concentration in these materials is essential for device performance.

Purpose of the Study:

• To present a novel, annealing-free charge transfer doping method for atomically thin indium oxide (In₂O₃).
• To investigate the effect of channel thickness on doping efficiency using viologen.
• To demonstrate the application of this doping method in electronic devices.

Main Methods:

• Utilized viologen, an organic compound with high reduction potential, for charge transfer doping of In₂O₃.
• Investigated the influence of In₂O₃ channel thickness on doping efficiency.
• Fabricated and characterized an n-type metal oxide semiconductor inverter using viologen-doped In₂O₃.

Main Results:

• Achieved an electron sheet density of 6.8 × 10¹² cm⁻² in 2 nm In₂O₃ devices without compromising carrier mobility.
• Demonstrated that doping efficiency increases with decreasing channel thickness due to higher surface-to-volume ratio.
• Showcased a reversible doping process by easily removing viologen with acetone.
• Developed a viologen-doped In₂O₃ inverter with a voltage gain of 26 at V<0xE1><0xB5><0x83> = 5 V.

Conclusions:

• Viologen charge transfer doping provides an effective and reversible method to control carrier concentration in atomically thin In₂O₃.
• The process is highly sensitive to channel thickness, offering tunable doping.
• This technique is promising for developing advanced electronic devices and next-generation applications.