Electron effective masses in 4H SiC

Abstract

Results from optically detected cyclotron resonance (ODCR) studies of electron effective masses in 4H SiC are reported. ODCR measurements were performed on high-purity n-type 4H SiC epitaxial layers grown by chemical vapor deposition at both X band (9.23 GHz) and Q band (35.05 GHz) microwave frequencies. Electron effective masses in 4H SiC were directly determined as m⊥*=0.42m0 and m∥*=0.29m0. A scattering time in the basal plane τ⊥≊4.3×10−11 s, and hence, the corresponding electron mobility μ⊥≊1.8×105 cm2/V s, was obtained from a fit of the ODCR line shape.

Science, Engineering, and Mathematics (SEM) at the Timbuktu Academy

“…9, and (b) these results almost perfectly reproduce those of Ref. 40. The significance of these points stems from the fact that they clearly indicate that corrections expected from the application of the BZW procedure are negligible for metallic Ru0 2 * unlike in the case of semiconductors.…”

“…Consequently, our calculated total density of states (DOS) in Fig. 10 are the same as those of Glassford and Chelikowsky 40 -in qualitative and quantitative terms. These authors did not provide the partial density of states (PDOS) we show in Fig.…”

“…We ascribe the difference between previous LDA results and experiments to the effect circumvented by the BZW procedure as noted above. 9.27 9.4 [42] 0.42 [40] 0.33 ± 0.01 [46] 0.29 [40] 0.58 ±0.01 [46] 0.31 ± 0.01 [46] The effective mass is a measure of the curvature of the calculated bands. The agreement between calculated and measured effective masses indicates an accurate determination of the shape of the bands.…”

Band-structure analysis of the conduction-band mass anisotropy in 6Hand 4HSiC

“…Son et al 5 also reported an ODCR signal using a higher microwave frequency in the Q-band (ν = 35 GHz). With the correspondingly higher ωτ = 9.1 value, our calculations predict that the mass anisotropy in the c-plane should be clearly resolved for 4H, as can be seen in Fig.…”

“…Rather conflicting results have been reported on the effective masses as determined by a fitting of IR absorption spectra of the excited shallow donor states 3,4 and by optically detected cyclotron resonance (ODCR). 5,6 In this letter, calculated band structures of 6H SiC and 4H SiC are used to determine the effective mass tensors at the conduction-band minimum. Our results are in good agreement with the ODCR results on the anisotropies with respect to the c-axis for 6H and 4H SiC masses and hence support a mass-anisotropy as the cause for the mobility anisotropies.…”