Temperature-dependent ultraviolet Raman scattering and anomalous Raman phenomenon of AlGaN/GaN heterostructure

Yanli Liu; Dunjun Chen; Guangfen Wei; Zhonghai Lin; Aixiang He; Meihua Li; Pingjian Wang; Rong Zhang; Youdou Zheng

doi:10.1364/OE.27.004781

Temperature-dependent ultraviolet Raman scattering and anomalous Raman phenomenon of AlGaN/GaN heterostructure

Opt Express. 2019 Feb 18;27(4):4781-4788. doi: 10.1364/OE.27.004781.

Authors

Yanli Liu, Dunjun Chen, Guangfen Wei, Zhonghai Lin, Aixiang He, Meihua Li, Pingjian Wang, Rong Zhang, Youdou Zheng

PMID: 30876088
DOI: 10.1364/OE.27.004781

Abstract

Temperature-dependent ultraviolet (UV) Raman scattering from AlGaN/GaN heterostructure is investigated. Compared to the visible Raman spectrum, four new peaks at 600, 700, 780, and 840 cm^-1 are observed in the UV Raman spectrum. The peak at 780 cm^-1 is from the AlGaN A₁(LO) mode. According to the calculated dispersion relations of the interface phonon modes in the AlGaN/GaN heterostructure, the peaks at 600 and 840 cm^-1 correspond to interface phonon modes. Meanwhile, the peak at 700 cm^-1 is attributed to the disorder-active mode near the 2DEG interface. Due to the near-resonant enhancement effect, the intensities of the GaN A₁(LO) mode, interface phonon modes, disorder active mode and the AlGaN A₁(LO) mode exhibit different temperature dependence. Furthermore, the frequencies of the interface phonon modes and the disorder active mode show anomalous temperature dependence, which can be attributed to the strong built-in electric field near the 2DEG interface.