Electron effective mass in Al0.72Ga0.28N alloys determined by mid-infrared optical Hall effect

Abstract

The effective electron mass parameter in Si-doped Al0.72Ga0.28N is determined to be m∗=(0.336±0.020) m0 from mid-infrared optical Hall effect measurements. No significant anisotropy of the effective electron mass parameter is found supporting theoretical predictions. Assuming a linear change of the effective electron mass with the Al content in AlGaN alloys and m∗=0.232 m0 for GaN, an average effective electron mass of m∗=0.376 m0 can be extrapolated for AlN. The analysis of mid-infrared spectroscopic ellipsometry measurements further confirms the two phonon mode behavior of the E1(TO) and one phonon mode behavior of the A1(LO) phonon mode in high-Al-content AlGaN alloys as seen in previous Raman scattering studies.