Temperature-Dependent Characterization of 2-DEG for Single- and Double-Channel GaN on SiC HEMTs
摘要
This study investigates two-dimensional electron gas (2-DEG) transport characteristics in single-channel and double-channel GaN high-electron-mobility transistors (HEMT)s created on SiC substrates, focusing on how these features change with temperature. The analysis of the band profile and electron distribution employed Poisson’s equation alongside Fermi–Dirac statistics. This process included deriving carrier distribution profiles Nc-v from capacitance–voltage (C–V) measurements conducted at various temperature settings. The effective mobility µe of the 2-DEG was determined through on-wafer measurements, taking into account input behavior, threshold voltage (Vt), output conductance (gds), transconductance (gm), gain, and cutoff frequency (fT). The single-channel devices featured a 2-DEG located 18 nm from the Schottky gate, demonstrating a peak carrier concentration of 17.44 × 1013 cm−2 and peak effective mobility of 980 cm2 V−1 s−1 at 40°C. The dual-channel devices exhibited two corresponding peaks in carrier distribution at 18 nm and 39 nm, with the latter demonstrating a higher carrier concentration of 23.5 × 1013 cm−2. The effective mobility value decreased from 1230 cm2 V−1 s−1 at −40°C to 860 cm2 V−1 s−1 at 150°C. Both single- and dual-channel devices exhibited temperature-dependent mobility and carrier distribution corresponding to semiconductor scattering mechanisms. The derived experimental mobility values aligned with the Hall effect measurements, validating the analysis and confirming its credibility. This study highlights the critical importance of structural design, material properties, and operating conditions in enhancing the performance of GaN HEMTs.