Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational...

Area of Science:

• Materials Science
• Solid State Physics
• Computational Materials Science

Background:

• Optical centers in aluminum nitride (AlN) exhibit complex charge states and interactions with other defects.
• Controlling specific optical centers while suppressing unwanted defects is crucial for AlN applications.

Purpose of the Study:

• To develop a workflow for engineering point defects in AlN crystal growth.
• To investigate chromium (Cr), manganese (Mn), and oxygen (O) induced optical centers in AlN.
• To provide a method for tuning defect concentrations and optical signatures through growth parameter control.

Main Methods:

• Combining CALPHAD-based phase analysis with *ab initio* defect calculations.
• Investigating point defect formation as a function of process parameters (e.g., nitrogen partial pressure).
• Calculating charge transition levels and optical signatures of dominant defects.

Main Results:

• Cr_Al and Mn_Al defects are dominant with increasing nitrogen partial pressure; nitrogen fugacity tunes optical signature intensity.
• Calculated Cr_Al charge transition levels (2.60 eV, 3.83 eV, 5.41 eV) and associated luminescence bands (2.82, 1.91, 3.15 eV).
• Mn_Al-V_N is abundant after Mn_Al; O_N-V_Al defects yield near-UV emissions (3.17, 3.26, 3.81 eV).

Conclusions:

• The developed workflow effectively predicts and controls point defects in AlN.
• Growth conditions, particularly nitrogen fugacity, can be optimized to tune specific optical centers.
• Results align with experimental optical signatures, offering pathways for defect engineering in AlN.