Oxygen-Assisted B-N Codoping Enables Shallow BN₂ Donors for n-Type Diamond

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Research

Background:

• Stable n-type conductivity in diamond is a long-standing challenge due to deep donor levels and dopant compensation.
• Conventional doping methods have failed to achieve reliable n-type behavior in diamond.

Purpose of the Study:

• To develop a method for achieving stable n-type conductivity in diamond.
• To investigate the potential of oxygen-assisted boron-nitrogen codoping (BN2) for creating shallow donors in diamond.

Main Methods:

• Microwave plasma chemical vapor deposition (MPCVD) with oxygen-assisted B-N codoping.
• First-principles calculations to identify and characterize the BN2 donor complex.
• Experimental optimization of the growth window for BN2 codoping.

Main Results:

• Identified BN2 as a shallow, strain-tolerant donor stabilized by oxygen, suppressing deeper defects.
• Achieved reproducible electron conduction with concentrations >10^19 cm^-3 and mobility of 4.05 cm^2/(V·s).
• Demonstrated a diamond-based pn junction with p-type 2H-MoTe2 exhibiting rectifying behavior.

Conclusions:

• Oxygen-assisted B-N codoping is a viable strategy for realizing n-type diamond.
• The shallow activation energy (~21.1 meV) of BN2 donors facilitates effective n-type transport.
• Interface quality is critical for future diamond electronic devices, paving the way for high-performance applications.