Phonon Scattering by Dislocations in GaN.

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Device Physics

Background:

• Crystal imperfections like dislocations critically affect gallium nitride (GaN) device performance and thermal transport.
• Accurate modeling of thermal conductivity is essential for optimizing GaN-based electronic and optoelectronic devices.

Purpose of the Study:

• To re-evaluate the influence of dislocations on thermal conductivity in GaN devices.
• To develop a computationally practical yet accurate method for predicting phonon scattering rates due to dislocations.

Main Methods:

• Utilized a Green's function approach with ab initio interatomic force constants.
• Employed density functional theory for three-phonon and point defect scattering calculations.
• Approximated dislocation scattering using semiempirical potentials.

Main Results:

• Experimental data on thermal conductivity in GaN can be explained by film thickness and point defect concentrations, alongside boundary scattering.
• The contribution of boundary scattering to thermal conductivity reduction in GaN was previously underestimated.
• The Green's function method with semiempirical potentials provides a practical and accurate way to quantify dislocation scattering.

Conclusions:

• Dislocation scattering effects on GaN thermal conductivity are well-approximated by semiempirical potentials within a Green's function framework.
• This approach offers a computationally feasible method for precise phonon scattering rate calculations.
• Refined understanding of scattering mechanisms is crucial for advancing GaN device thermal management.