High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

Area of Science:

• Materials Science
• Semiconductor Physics
• Optoelectronics

Background:

• Gallium Nitride (GaN) based materials are crucial for optoelectronic devices.
• Gallium Oxide (β-Ga2O3) is a promising substrate material due to its wide bandgap and conductivity.
• Achieving high-quality InxGa1-xN epilayers on β-Ga2O3 is challenging.

Purpose of the Study:

• To investigate the growth of InxGa1-xN epilayers on conductive and transparent (01)-oriented β-Ga2O3 substrates.
• To evaluate the structural and optical properties of the grown epilayers.
• To assess the potential of this heterostructure for vertical light-emitting device applications.

Main Methods:

• Growth of InxGa1-xN epilayers (0 ≤ x ≤ 23) using a low-temperature GaN buffer layer on (01)-oriented β-Ga2O3.
• Raman spectroscopy for uniformity and relaxation analysis.
• Transmission Electron Microscopy (TEM) for dislocation density and behavior.
• Photoluminescence (PL) and time-resolved spectroscopy for optical quality assessment.

Main Results:

• Low-temperature GaN buffer layer improved crystal quality and stability compared to AlN buffer or (100)-oriented substrates.
• Raman maps indicated a relaxed and uniform 2″ wafer.
• TEM revealed significantly reduced dislocation density (~4.8 × 10^7 cm⁻²) and specific dislocation annihilation mechanisms.
• High optical quality confirmed by PL, with recombination governed by bound excitons.
• Achieved low root-mean-square roughness (≤1.5 nm) for InxGa1-xN epilayers.

Conclusions:

• The (01)-oriented β-Ga2O3 substrate with a low-temperature GaN buffer is suitable for high-quality InxGa1-xN epilayer growth.
• The observed dislocation behavior contributes to improved material quality.
• This heterostructure demonstrates strong potential for large-scale, high-quality vertical light-emitting device design.