Temperature-dependent Hall-effect data.
HVPE GaN (sample 2057). The measured values (solid circles) were corrected using a two-layer model (empty squares) with μ = (44.5 ± 5.0) cm2/Vs and n□/d = (2.72 ± 0.25) × 1017 cm−3 for the degenerate interface layer, where n□ is the sheet electron concentration and d = 24 μm is the total GaN thickness. The solid line is fit using ND = 1 × 1017 cm−3, NA = 5 × 1016 cm−3, and ED = 14 meV. The error bars reflect the uncertainty in μ and n in the degenerate layer estimated from the low-temperature data where the bulk conductivity is negligible. (a) The concentration of free electrons n, (b) the electron mobility μ.