P-Type Lithium Niobate Thin Films Fabricated by Nitrogen-Doping

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Technology

Background:

• Lithium niobate (LiNbO₃) is a crucial material in optoelectronics, but achieving p-type conductivity has been challenging.
• Developing novel semiconductor materials with controlled doping is essential for advanced electronic devices.

Purpose of the Study:

• To fabricate nitrogen-doped lithium niobate (LiNbO₃:N) thin films on a silicon substrate.
• To investigate the structural, electrical, and chemical properties of the fabricated films.
• To demonstrate the potential for p-type conductivity in LiNbO₃:N for optoelectronic applications.

Main Methods:

• Pulsed Laser Deposition (PLD) with a radio-frequency nitrogen plasma beam was used for film fabrication.
• X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM) were employed for structural and surface characterization.
• Hall-effect measurements and X-ray Photoelectron Spectroscopy (XPS) were used to determine electrical properties and chemical composition.

Main Results:

• Polycrystalline LiNbO₃:N films with (012) and (104) orientations were successfully grown on Si-substrates.
• Hall-effect measurements confirmed a rare p-type conductivity with a hole concentration of 7.31 × 10¹⁵ cm⁻³ and mobility of 266 cm²V⁻¹s⁻¹.
• XPS analysis showed 0.87% nitrogen content, with N atoms likely substituting O sites, contributing to the observed p-type behavior.

Conclusions:

• The successful fabrication of p-type LiNbO₃:N thin films on Si substrates opens new avenues for semiconductor research.
• This achievement is a significant step towards the development of novel p-n junction devices and integrated optoelectronics.
• The findings highlight the potential of nitrogen doping to engineer the electronic properties of lithium niobate for advanced applications.