Low-Frequency Noise Characteristics of GaN Nanowire Gate-All-Around Transistors With/Without 2-DEG Channel

Two different lateral GaN-based nanowire gate-all-around transistors with and without 2-D electron gas (2-DEG) channel were fabricated using top-down approach, and their noise characteristics were investigated. The nanowire transistor with 2-DEG channel had a relatively larger channel cross section, which consists of regrown AlGaN/GaN plateau on the trapezoidal GaN layer, and exhibited negative threshold voltages (V
_th
). The transistor without 2-DEG channel consisted only GaN layer with triangular-shaped smaller channel cross section and exhibited a positive V
_th
. Both nanowire transistors clearly demonstrated typical 1/f noise characteristics, but the AlGaN/GaN nanowire transistor with 2-DEG channel showed larger noise magnitude. The noise characteristics of both devices are well explained by the carrier number fluctuation with correlated mobility fluctuation model. Using this model, the interface trap densities and the remote Coulomb scattering parameters were extracted, revealing a worse interface quality for the AlGaN/GaN device on the one hand, but stronger scattering for the narrow GaN transistor on the other hand.