2015/12/04 by S. Schöche, Schöche, S., Tino Hofmann +15
Engineering · Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Semiconductor materials and devices #Semiconductor materials and interfaces #Silicon Carbide Semiconductor Technologies
paper · pdf · doi:10.48550/arxiv.1512.01427
openalex publication_date 2015/12/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The phonon mode parameters and anisotropic mid-infrared dielectric function tensor components of high- Al-content AlxGa1-xN alloys in dependence of the Al content x are precisely determined from mid-infrared spectroscopic ellipsometry measurements for a set of high-quality Si-doped AlxGa1-xN epitaxial layers on 4H-SiC substrates. Two-mode behavior of the E1(TO) modes and one-mode behavior of the A1(LO) mode are found in agreement with previous Raman scattering spectroscopy reports. The composition dependencies of the IR active phonon frequency parameters are established and a discussion on the silent B1 mode that may be disorder activated is provided. The static dielectric constants in dependence of x are determined by using the best-match model derived phonon mode frequency and high-frequency dielectric constant parameters and applying the Lydanne-Sachs-Teller relation. The effective mass parameter in high-Al-content AlxGa1-xN alloys and its composition dependence are determined from mid-infrared optical Hall effect measurements. Furtheremore, the free electron concentration N and mobility parameters μ of AlxGa1-xN films with similar Si doping levels are investigated as function of the Al content, x and discussed.