Local atomic structure analysis around Mg atom doped in GaN by X-ray absorption spectroscopy and spectrum simulations

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Research

Background:

• Gallium nitride (GaN) is crucial for power devices.
• Achieving p-type conductivity in GaN requires magnesium (Mg) doping.
• Understanding Mg and hydrogen (H) incorporation sites is vital for device performance.

Purpose of the Study:

• To identify the specific lattice site of incorporated magnesium (Mg) in gallium nitride (GaN).
• To determine the feasibility of detecting hydrogen (H) near Mg sites using X-ray absorption spectroscopy (XAS).
• To correlate Mg and H incorporation with p-type formation in GaN.

Main Methods:

• Utilized high-sensitivity, high-resolution X-ray absorption spectroscopy (XAS) with a superconducting tunnel junction array detector.
• Successfully separated the Mg fluorescence signal from the Ga signal in dilute Mg-doped GaN samples (3 × 10^19 atoms cm^-3).
• Employed density functional theory (DFT) to simulate XAS spectra for comparison with experimental data.

Main Results:

• Identified the incorporated Mg atoms occupying the gallium (Ga) substitutional site within the GaN lattice.
• Obtained clear Mg K-edge XAS spectra from highly dilute Mg-doped GaN samples.
• Demonstrated that spectral features can distinguish the presence or absence of hydrogen (H) around the Mg atoms.

Conclusions:

• X-ray absorption spectroscopy is a powerful tool for site-specific analysis of dilute dopants in semiconductors.
• Magnesium (Mg) preferentially incorporates at the Ga substitutional site in GaN.
• The method shows potential for in-situ monitoring of hydrogen (H) passivation in p-type GaN.