ZrO₂ Based Multilayered Stacks with Al₂O₃, Y₂O₃ or La₂O₃ Interlayers for SiC Power Devices.

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Zirconium dioxide (ZrO2) is a high-k dielectric material suitable for silicon carbide (SiC) power devices.
• However, ZrO2 suffers from low breakdown fields and high leakage currents in thicker layers, limiting its application.
• Effective dielectric layers are crucial for enhancing the performance and reliability of SiC power devices.

Purpose of the Study:

• To suppress leakage current in ZrO2 films for SiC power devices.
• To investigate the impact of Al2O3, Y2O3, and La2O3 interlayers on ZrO2 dielectric properties.
• To optimize the dielectric performance of ZrO2-based stacks for high-voltage applications.

Main Methods:

• Fabrication of ZrO2 films integrated with thin interlayers of Al2O3, Y2O3, or La2O3.
• Electrical characterization including leakage current measurements and breakdown field determination.
• Analysis of film structure and thermal stability using techniques like X-ray diffraction (XRD) and transmission electron microscopy (TEM).
• Capacitance-Voltage (C-V) measurements to assess charge trapping effects.

Main Results:

• Integration of Al2O3, Y2O3, or La2O3 interlayers significantly reduced charge carrier transport and leakage current in ZrO2 films.
• The Al2O3 interlayer demonstrated the most significant improvement, reducing leakage current by two orders of magnitude.
• The optimized Al2O3-ZrO2 stack achieved a high breakdown field of 7.4 MV/cm and a dielectric constant of 13.
• The amorphous nature of the nanolaminate structure increased the crystallization temperature to 750 °C.
• Capacitance-Voltage measurements indicated no additional charge trapping, and optimized deposition reduced trapping by 50% compared to pure ZrO2.

Conclusions:

• Thin Al2O3 interlayers effectively suppress leakage current and enhance the breakdown field of ZrO2 dielectrics for SiC power devices.
• The nanolaminate structure's amorphous nature and improved thermal stability are key to its superior performance.
• This approach offers a promising pathway for developing reliable high-k dielectrics for advanced SiC power electronics.
• The optimized stack exhibits excellent dielectric properties without detrimental charge trapping effects.