Determination of the electron trap level in Fe-doped GaN by phonon-assisted conduction phenomenon

TL;DR

This study identifies the E3 trap level in Fe-doped GaN as the origin of thermally activated conduction by using acoustic resonance to measure activation energy, revealing phonon-assisted conduction mechanisms.

Contribution

The paper introduces a non-contact acoustic resonance method to determine trap energy levels in Fe-doped GaN, specifically identifying the E3 level as responsible for TAC.

Findings

Activation energy of 0.54 eV for TAC in Fe-doped GaN.

Identification of the E3 trap level as the conduction origin.

Measurement of elastic constants at high temperatures.

Abstract

We acoustically measured the energy level for thermally activated conduction (TAC) in high-resistivity Fe-doped GaN using the non-contacting antenna-transmission acoustic-resonance method. The acoustic attenuation takes a maximum at a specific temperature, where the TAC is accelerated with the help of phonon energy. The Debye type relaxation is thus observed for acoustic attenuation, and its activation energy (0.54$\pm$0.04 eV) was determined with attenuation measurements at various frequencies and temperatures. This value agrees with the E3 level in GaN, indicating that thermally associated conduction originates from the E3 trap level. We also measured the five independent elastic constants at high temperatures.