Insight into the High Hole Concentration of p-Type Ga₂O₃ via In Situ Nitrogen Doping

Area of Science:

• Materials Science
• Semiconductor Physics
• Oxide Electronics

Background:

• The development of reliable p-type Gallium Oxide (Ga2O3) is crucial for advancing high-voltage electronic devices.
• Current challenges include an unclear p-type conduction mechanism and difficulty in achieving stable p-type doping.

Purpose of the Study:

• To demonstrate a method for achieving reliable p-type conductivity in Ga2O3.
• To elucidate the mechanism behind p-type conduction in nitrogen-doped Ga2O3.

Main Methods:

• In situ nitrogen (N) doping was performed during metal-organic chemical vapor deposition (MOCVD) homoepitaxy of Ga2O3.
• Nitrous oxide (N2O) was used as both the oxygen source and the acceptor dopant.
• Structural and compositional analyses were employed to verify nitrogen incorporation and its effects.

Main Results:

• Efficient nitrogen incorporation was confirmed, forming N-Ga bonds and compensating residual Si/H donors without degrading crystal quality.
• Achieved excellent p-type performance with a hole concentration of 1.04 × 10^18 cm^-3 and mobility of 0.47 cm^2 V^-1 s^-1 at room temperature.
• Determined an activation energy of 0.168 eV for the p-type conductivity.

Conclusions:

• A novel mechanism for p-type conduction in Ga2O3 is proposed, involving crystallographic visualization of N^2- acceptors and O^- holes.
• Suppression of donor compensation and precise control of nitrogen chemical potential are key to achieving high-hole-concentration p-type conduction.
• The findings pave the way for Ga2O3-based power electronics by enabling reliable p-type material.