Thermal phonon modulation of III-nitride semiconductors under strong electric fields

Abstract

Self-heating effects in high-power III-nitride semiconductor electronics and optoelectronic devices limit their practical applications, while phonon modulation can be used to alleviate heat dissipation problems. In this paper, we report our efforts to suppress macroscopic polarization fields when applying strong electric fields, which affect the phonon frequency. We investigate alterations in phonon frequencies for two materials, 2H-GaN and 2H-AlN, for various electric field strengths ranging from 0.00 V/Å to 0.07 V/Å and 0.00 V/Å to 0.18 V/Å, respectively. We also analyze the changes in the macroscopic dielectric tensor and the BORN effective charge tensor. The calculation results reveal that the vibration frequencies of the longitudinal-optical (LO) A1(LO) mode are decreased by approximately 2 cm−1 for 2H-GaN and 3 cm−1 for 2H-AlN. Our simulation results are consistent with the Raman spectroscopy results of Si-doped 2H-GaN specimens illuminated with 325 nm excitation for a variety of carrier concentrations. This study contributes to a better understanding of the factors influencing phonon behavior, thus offering new methods for optimizing the thermal regulation and dissipation patterns of III-nitride semiconductor materials and devices.

Keywords

• First-principles calculations
• III-nitride semiconductor
• High electric fields
• Phonon modulation
• Raman spectroscopy